PVED-CL Controller for Electro-hydraulic Steering

MAKING MODERN LIVING POSSIBLE
Operation Manual
PVED-CL Controller
for Electro-Hydraulic Steering,
Version 1.38
powersolutions.danfoss.com
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Revision History
Table of Revisions
2
Date
Changed
Rev
11 Jan 2010
Major changes. For PVED-CL software release 1.38
CA
05 May 2007
Major changes. For PVED-CL software release 1.28
BA
01 Nov 2006
First edition. For PVED-CL software release 1.26
AA
11025583 • Rev CA • 11 Jan 2010
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Contents
General Information
Safety Considerations
Definitions and Abbreviations.....................................................................................................................................................8
Reference Documents.................................................................................................................................................................... 8
Introduction to Electrohydraulic Steering...............................................................................................................................8
EH steering valve.........................................................................................................................................................................9
EHPS steering valve piloted with electric actuator PVE and/or steering unit....................................................... 9
PVG 32 Proportional valve....................................................................................................................................................... 9
PVG 100 Proportional valve.................................................................................................................................................. 10
PVED-CL........................................................................................................................................................................................10
Steering Possibilities..................................................................................................................................................................... 10
Input Devices/Controllers......................................................................................................................................................10
Programs......................................................................................................................................................................................10
Interface Overview.........................................................................................................................................................................11
Application Examples...................................................................................................................................................................11
Wheel Loader............................................................................................................................................................................. 11
Tractor...........................................................................................................................................................................................12
CAN Interface...................................................................................................................................................................................12
Bus Architecture Considerations.........................................................................................................................................12
Power-up..................................................................................................................................................................................... 12
CAN-bus Sensor Power-up Synchronization.................................................................................................................. 12
CAN-bus Protocol..................................................................................................................................................................... 13
PVED-CL Input Interface ........................................................................................................................................................13
Output Interface .......................................................................................................................................................................13
Battery...........................................................................................................................................................................................13
Actuator Position Sensor....................................................................................................................................................... 13
Functional Options Overview....................................................................................................................................................14
Safety Considerations...................................................................................................................................................................15
On-road Operation...................................................................................................................................................................15
Vehicle Speed Sensor..............................................................................................................................................................15
Closed-loop Operation........................................................................................................................................................... 15
Analogue Input Sensors (Joystick or Wheel Angle Sensor).......................................................................................15
Risk assessment.........................................................................................................................................................................16
Configuration and Adjustment
Configuration and Adjustment.................................................................................................................................................17
Parameter Tuning Process.....................................................................................................................................................17
Changing Default Parameters................................................................................................................................................... 17
System Parameters...................................................................................................................................................................17
Steering Device Parameters..................................................................................................................................................18
Program Parameters................................................................................................................................................................18
Indexing Parameter................................................................................................................................................................. 19
Reading and Writing Parameters............................................................................................................................................. 20
Program Transition Control........................................................................................................................................................20
System State............................................................................................................................................................................... 20
Select Program/Program Transition........................................................................................................................................20
Program Transition Acknowledge........................................................................................................................................... 21
How does the PVED work?..........................................................................................................................................................21
Electronic Control Unit........................................................................................................................................................... 21
Solenoid Valve Bridge............................................................................................................................................................. 21
Control Principle....................................................................................................................................................................... 22
Inductive Transducer, LVDT (Linear Variable Differential Transformer)............................................................... 22
Integrated Pulse Width Modulation.................................................................................................................................. 22
LED................................................................................................................................................................................................. 22
Technical Specification
Technical Data.................................................................................................................................................................................24
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Contents
Installation
Steering Device Transition
Installation........................................................................................................................................................................................ 25
Connector Interface................................................................................................................................................................. 25
Valve Interface.................................................................................................................................................................................25
Valve calibration objectives.................................................................................................................................................. 26
Dead-band crossing.................................................................................................................................................................26
Valve types overview...............................................................................................................................................................26
Valve transfer function............................................................................................................................................................26
Valve interface parameters................................................................................................................................................... 27
Valve calibration methods..........................................................................................................................................................28
Method 1: Conservative software dead-band values..................................................................................................28
Example: Determine the general software dead-bands for a series of PVED-CL / EH valve with a
dynamic spool:...................................................................................................................................................................28
Method 2: Manual software dead-band calibration.................................................................................................... 28
Method 3: Valve auto-calibration....................................................................................................................................... 29
Preconditions:............................................................................................................................................................................ 29
Valve auto-calibration command parameters............................................................................................................... 30
Valve auto-calibration procedure.......................................................................................................................................30
Suggested valve auto-calibration command values................................................................................................... 31
Valve auto-calibration quick-guide......................................................................................................................................... 32
Valve auto-calibration procedure.......................................................................................................................................32
Parameter tuning order..........................................................................................................................................................32
Verification of auto-calibration result stability...............................................................................................................32
Verification of the open-loop performance.................................................................................................................... 32
Verification of the closed-loop performance..................................................................................................................33
Logging and monitoring........................................................................................................................................................33
Explanation: ............................................................................................................................................................................... 33
Mapping a Steering Device........................................................................................................................................................ 34
Only one signal per analogue channel can be acquired............................................................................................34
Analogue Interface........................................................................................................................................................................ 35
AD Signal Interface Requirements..................................................................................................................................... 35
Scaling Analogue Signals.......................................................................................................................................................35
Linear Transfer Characteristic (3-Point)............................................................................................................................ 35
Non-Linear Transfer Characteristic (5-Point).................................................................................................................. 36
Steering Actuator Position Signal.......................................................................................................................................37
Analogue Input Drift Compensation.................................................................................................................................37
Transmitting the Voltage Readings on CAN................................................................................................................... 38
Steering Device Transition..........................................................................................................................................................39
Threshold Definition..................................................................................................................................................................... 39
Define the Maximum Steering Motion Speed.....................................................................................................................39
Define the Steering Motion Threshold...................................................................................................................................40
Steering Wheel Sensor Noise Gate
Retrieving Steering Device Information................................................................................................................................ 41
Steering Wheel Sensor Noise Gate.......................................................................................................................................... 41
Example:.......................................................................................................................................................................................41
Steering by Steering Wheel – Open Loop
Steering by Steering Wheel – Open Loop.............................................................................................................................42
Acquire the Signals.................................................................................................................................................................. 42
Functionality Tree.......................................................................................................................................................................... 42
Open Loop Control........................................................................................................................................................................43
Select the Control Principle........................................................................................................................................................43
Apply Backlash...........................................................................................................................................................................44
Set-point Transfer Function....................................................................................................................................................... 44
Steering Sensitivity........................................................................................................................................................................45
Select a Fixed Sensitivity............................................................................................................................................................. 45
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Contents
Select a Sensitivity with Relation to Actuator Position ....................................................................................................46
Select a Sensitivity with Relation to Vehicle speed............................................................................................................47
Ramps (Anti-jerk)............................................................................................................................................................................48
Ramps with Fixed Ramp Times................................................................................................................................................. 48
Example: ......................................................................................................................................................................................49
Example: ......................................................................................................................................................................................50
Select Ramps with Ramp Times Related to Vehicle Speed............................................................................................. 50
Example: ......................................................................................................................................................................................52
Example: ......................................................................................................................................................................................52
Anti-jerk Ramp Parameter Tuning Guide.........................................................................................................................53
Soft (Cushion) End-stop...............................................................................................................................................................53
Main Spool Dead-band Control Function............................................................................................................................. 54
Dead-band Jump Control......................................................................................................................................................55
Dead-band Hold and Proportional Control.................................................................................................................... 55
Responding to Flow Requests after Tolsout................................................................................................................... 55
Magnetic Valve Control............................................................................................................................................................... 55
Steering by Steering Wheel – Closed Loop
Steering by Steering wheel – Closed Loop...........................................................................................................................56
Functionality Tree.......................................................................................................................................................................... 56
Select the Control Principle........................................................................................................................................................57
Acquire the Signals.................................................................................................................................................................. 57
Apply Backlash...........................................................................................................................................................................57
Steering Sensitivity........................................................................................................................................................................58
Select a Fixed Steering Sensitivity........................................................................................................................................... 58
Select a Sensitivity with Relation to Vehicle Speed........................................................................................................... 58
Create the Set-point......................................................................................................................................................................60
Closing the Loop............................................................................................................................................................................ 61
Feed-forward..............................................................................................................................................................................61
Steady State Error..................................................................................................................................................................... 61
To achieve steady state accuracy:.......................................................................................................................................61
Proportional Band.................................................................................................................................................................... 61
Steering Wheel Knob Position Control.................................................................................................................................. 63
What makes the steering wheel drift?.............................................................................................................................. 63
Eliminate Noise due to Frequent Pressure Build-up......................................................................................................... 63
Magnetic Valve Control............................................................................................................................................................... 64
Steering by High Priority Steering Device – Open Loop
Steering by High Priority Steering Device – Open Loop..................................................................................................65
Functionality Tree.......................................................................................................................................................................... 65
Select the Control Principle........................................................................................................................................................66
Acquire the Signals.................................................................................................................................................................. 67
Set-point Transfer Function....................................................................................................................................................... 67
Steering Sensitivity........................................................................................................................................................................68
Select a Fixed Sensitivity............................................................................................................................................................. 68
Select a Sensitivity with Relation to the Actuator Position.............................................................................................69
Select a Sensitivity with Relation to Vehicle Speed........................................................................................................... 70
Ramps (Anti-Jerk)........................................................................................................................................................................... 71
Select Ramps with Fixed Ramp Times.................................................................................................................................... 72
Example: ......................................................................................................................................................................................72
Example: ......................................................................................................................................................................................72
Select Ramps with Ramp Time Related to Vehicle Speed...............................................................................................73
Example: ......................................................................................................................................................................................75
Example: ......................................................................................................................................................................................75
Anti-jerk Ramp Parameter Tuning Guide.............................................................................................................................. 76
Soft (Cushion) End-stop...............................................................................................................................................................76
Spool Dead-band Hold Control Function ............................................................................................................................ 78
Dead-band Jump Control......................................................................................................................................................78
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PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Contents
Dead-band Hold and Proportional Control.................................................................................................................... 78
Responding to Flow Requests after Tolsout................................................................................................................... 78
Magnetic Valves OFF Control.................................................................................................................................................... 78
Resolving a Steering Control Conflict............................................................................................................................... 78
Steering by High Priority Steering Device – Closed Loop
Steering by High Priority Steering Device – Closed Loop .............................................................................................. 79
Functionality Tree.......................................................................................................................................................................... 79
Tracking........................................................................................................................................................................................80
Select the Control Principle........................................................................................................................................................80
Acquire the Signals.................................................................................................................................................................. 81
Create the Set Point...................................................................................................................................................................... 81
Closing the Loop............................................................................................................................................................................ 82
Eliminate Noise due to Frequent Pressure Build-up......................................................................................................... 82
Magnetic Valves OFF Control ................................................................................................................................................... 82
Resolving a Steering Control Conflict............................................................................................................................... 83
High Priority Steering Device Enable/Disable Control..................................................................................................... 83
System Requirements............................................................................................................................................................. 83
Device Diagnostic Operation............................................................................................................................................... 83
Enable or Disable Joystick Steering Device.....................................................................................................................84
Boot-up State of Steering Device........................................................................................................................................84
Getting the Actual Enable/disable Status of the Device............................................................................................ 84
Steering by Low Priority Steering Device – Open Loop
Steering by Low Priority Steering Device – Open Loop...................................................................................................85
Functionality Tree.......................................................................................................................................................................... 85
Select the Control Principle........................................................................................................................................................86
Acquire the Signals.................................................................................................................................................................. 87
Set-point Transfer Function....................................................................................................................................................... 87
Steering Sensitivity........................................................................................................................................................................88
Select a Fixed Sensitivity............................................................................................................................................................. 88
Select a Sensitivity with Relation to the Actuator Position.............................................................................................89
Select a Sensitivity with Relation to Vehicle speed............................................................................................................90
Ramps (Anti-jerk)............................................................................................................................................................................91
Ramps with Fixed Ramp Times................................................................................................................................................. 92
Example: ......................................................................................................................................................................................92
Example: ......................................................................................................................................................................................92
Select Ramps with Ramp Time Related to Vehicle Speed...............................................................................................93
Example: ......................................................................................................................................................................................95
Example: ......................................................................................................................................................................................95
Anti-jerk Ramp Parameter Tuning Guide.............................................................................................................................. 96
Soft (Cushion) End-stop...............................................................................................................................................................96
Spool Dead-band Hold Control Function............................................................................................................................. 98
Dead-band Jump Control......................................................................................................................................................98
Dead-band Hold and Proportional Control.................................................................................................................... 98
Responding to Flow Requests after Tolsout................................................................................................................... 98
Magnetic Valves OFF Control.................................................................................................................................................... 98
Resolving a Steering Control Conflict............................................................................................................................... 98
Steering by Low Priority Steering Device – Closed Loop
Steering by High Priority Steering Device – Closed Loop .............................................................................................. 99
Functionality Tree.......................................................................................................................................................................... 99
Tracking..................................................................................................................................................................................... 100
Select the Control Principle..................................................................................................................................................... 100
Acquire the signals................................................................................................................................................................ 101
Create the Set Point....................................................................................................................................................................101
Closing the Loop..........................................................................................................................................................................102
Eliminate Noise due to Frequent Pressure Build-up.......................................................................................................102
Magnetic Valves OFF Control..................................................................................................................................................102
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Contents
Resolving a Steering Control Conflict.............................................................................................................................103
Low Priority Steering Device Enable/Disable Control....................................................................................................103
System Requirements...........................................................................................................................................................103
Device Diagnostic Operation.............................................................................................................................................103
Enable or Disable Joystick Steering Device.................................................................................................................. 103
Boot-up State of Steering Device..................................................................................................................................... 104
Getting the Actual Enable/disable Status of the Device..........................................................................................104
Auto-steering
Reduced State
Auto-steering................................................................................................................................................................................ 105
Guidance Commands................................................................................................................................................................ 105
Calculating the Wheel Angle...................................................................................................................................................105
Closing the Loop..........................................................................................................................................................................106
Trimming the System.................................................................................................................................................................106
Noise due to Frequent Pressure Build-up...........................................................................................................................107
Select a Fixed Sensitivity...........................................................................................................................................................107
Vehicle Speed Dependent Sensitivity..................................................................................................................................107
Magnetic Valves OFF Control..................................................................................................................................................109
Resolving a Steering Control Conflict.............................................................................................................................109
SASA disengage ability check................................................................................................................................................. 109
Reduced State...............................................................................................................................................................................111
Reduced Steering Functionality.............................................................................................................................................111
High Priority Steering Device Fault..................................................................................................................................111
Low Priority Steering Device Fault...................................................................................................................................112
Vehicle Speed Sensor Fault................................................................................................................................................ 112
Steered Wheel Angle Sensor Fails....................................................................................................................................112
Diagnostic & Troubleshooting
Diagnostic...................................................................................................................................................................................... 114
Example on Resolving a Fault ...........................................................................................................................................114
Solution......................................................................................................................................................................................114
Troubleshooting.......................................................................................................................................................................... 114
Typical Fault Sources..................................................................................................................................................................114
J1939 Diagnostic Interface.......................................................................................................................................................115
AD1 and/or AD2 Short-circuit............................................................................................................................................117
Missing CAN Sensor Set-points.........................................................................................................................................117
Redundant Wheel Angle Sensor Values Deviate too much or CAN Sensor Set-point Data out of
Range.................................................................................................................................................................................. 118
Steering Wheel Speed Plausibility Check Failure....................................................................................................... 118
Vehicle Speed CAN Sensor Data Plausibility Check Failure.................................................................................... 118
Power Supply Voltage.......................................................................................................................................................... 118
Sensor Supply Voltage......................................................................................................................................................... 118
Loss of Main Spool Control or Spool Position Plausibility Check Failure...........................................................118
Internal PVED-CL Error..........................................................................................................................................................119
LED Diagnostic............................................................................................................................................................................. 119
Appendix
System Parameters..................................................................................................................................................................... 120
Program Parameters...................................................................................................................................................................124
Steering Device Parameters.................................................................................................................................................... 126
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PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Operation Manual
General Information
Definitions and Abbreviations
Definitions and Abbreviations
Term
Description
DTC
Diagnostic Trouble Code
ECU
Electronic Control Unit
EHPS
Electro-Hydraulic Power Steering
MMI
Man-Machine Interface
XID
Extended Message Identifier
PVED-CL
Proportional Valve Digital – Closed Loop – here the valve controller
SPN
Suspect Parameter Number
Reference Documents
Refering to Literature:
Reference
PVED-CL Communication Protocol version 1.38, 11025584
Introduction to Electrohydraulic Steering
As operator comfort receives higher and higher focus along with higher demands for automation, new
technologies are necessary to take on this challenge. The new technologies are using electro-hydraulics,
combining hydraulic power with electronics and computer power.
Electro-hydraulic steering system has the advantages over pure hydraulic steering systems such as the
ability to meet specific functionalities on request.
In order to give this functionality Danfoss has developed the PVED-CL which is a valve actuator with
integrated controller, designed to fit onto various Danfoss valves such as:
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
General Information
EH steering valve
•
•
•
Max flow: 40 l/min
Max steering pressure: 210 bar
Available as in-line and OSPE version
EHPS steering valve piloted with electric actuator PVE and/or steering unit
•
•
Flow capacity up to 100 l/min
Max steering pressure up to 250 bar
PVG 32 Proportional valve
•
•
Flow capacity up to 120 l/min
Max steering pressure: 350 bar
(Please contact Danfoss for further information.)
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
General Information
PVG 100 Proportional valve
•
•
Flow capacity up to 180 l/min
Max steering pressure: 350 bar
(Please contact Danfoss for further information.)
The advantage of having various valves that interfaces to the same valve actuator is a higher flexibility for
our customers needing different valve sizes and wanting to use the same valve actuator.
PVED-CL
The PVED-CL is a steering controller in the Danfoss valve actuator family. The steering controller is
designed to meet the functional requirements for steering - electro-hydraulically - any of-road vehicle by
following types of steering methods:
•
•
Steering with operator input via steering devices such as joystick, steering wheel sensor, mini-wheel
etc.
Automated steering with input from GPS, laser or row guidance controllers
The compact design of the PVED-CL reduce space, wiring, installation time, and provides the most
optimal location of any controller executing software to steer any vehicle. Especially when more than
with a one steering device is available in a vehicle or when closed-loop control is used, the advantage of
the controller being integrated in the valve becomes clear.
Steering Possibilities
Input Devices/Controllers
The PVED-CL allows up to four steering devices/controllers to be active in one system. For example:
Steering wheel and joystick steering in one system can both be connected to the PVED-CL.
The input steering device selection principle works as follows:
•
•
In case the operator wants to switch to a lower priority steering device / controller, the steering valve
must be in neutral (no steering) before it can switch to the requested steering device.
In case the operator wants to switch to a higher priority steering device/controller the switch will
happen instantaneously. This means that when several steering devices are operated, the input signal
of the steering device/controller with highest priority is always selected.
Programs
The PVED-CL provides, for each steering device, multiple separated set of control parameters (programs)
to leave the choice entirely up to the OEM’s to:
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
General Information
•
•
Select and program a control principle (open- or closed-loop) for each program for a particular
steering device
Select and program customized functionalities like variable steering ratio, ramp time, etc. for a
particular steering device.
Interface Overview
The PVED-CL provides the possibility for dynamic adjustment of the steering system by dynamically
applying a new set of control parameters from a program while driving. This allows the driver to optimize
the steering system to the working situation like; material handling, precision steering, fast driving and
anti jerk control for articulated steered vehicles. Up to 5 programs per steering device/controller (10 for
steering wheel sensor) are available. A man-machine interface (MMI) with a display with control buttons
provides means to request programs. The MMI transmits the specific commands via CAN bus.
Application Examples
Wheel Loader
The use of the PVED-CL on wheel loaders typically in conjunction with EHPS gives a range of functional
opportunities:
•
•
•
Anti-jerks functionality
Soft-stop at cylinder-end positions
Variable steering ratio – fixed mode
‒ Lower steering ratio during a load-cycle
‒ High steering ratio during a transport cycle
•
Variable steering ratio – speed dependant
‒ The higher driving speed - the higher the steering ratio
•
•
Joystick steering
Graceful degradation (operation in reduced mode)
‒ Allow faults to partly shut-down of steering functionality to maximize system performance for the
rest of the mission
Other articulated vehicles can have similar advantages.
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
General Information
Tractor
•
•
Auto-guidance with GPS, laser or row guidance controllers
Variable steering ratio - actuator dependant
‒ Lower steering ratio during load cycle
•
Variable steering ratio speed dependant
‒ The higher driving speed the higher ratio
•
Plug and perform GPS control
Storing the machine parameters in the PVED-CL allows a GPS controller to be moved between various
machines without re-adjusting the machine parameters.
•
•
Automated steering is the next step in automating the field work on farms. The automated steering
gives the following advantages
Longer operation time
Ensures that the machine works optimally (minimal waste).
CAN Interface
Bus Architecture Considerations
It is recommended to install the steering system on a separate bus as it is important to have enough CAN
bus bandwidth for all the input devices/controllers and the PVED-CL to work in an optimal way.
Power-up
Within 1500 ms after powering up, the PVED-CL is fully operational and transmits an Address claim
message on CAN-bus. Power-up is normally synchronized with engine start and allows to be executed
regardless any sensor input values. After power up the PVED-CL validates periodically the presence of all
CAN and analogue control signals with the ones mapped. In case a signal is not available or is invalid, the
PVED-CL enters fault-mode or optionally a reduced state, where operation is continued with reduced
steering functionality. After successful power-up, the main spool inside the valve is first operated when a
steering device is operated.
CAN-bus Sensor Power-up Synchronization
The PVED-CL can be configured to wait up to 10000 ms for a CAN message. This is to accommodate for
slow-starting CAN devices which are transmitting data to the PVED-CL.
Please see device dependent parameters HPStwPowerUpTimeout, HPStdPowerUpTimeout,
LPStdPowerUpTimeout, WAPowerUpTimeout and VSPowerUpTimeout in System Parameters on page
120.
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
General Information
CAN-bus Protocol
The PVED-CL conforms to CAN-bus standard J1939. Relevant J1939 compliance issues are explained in
PVED-CL Communication Protocol, 11025584.
For details on parameter changes, refer to Changing Default Parameters on page 17.
PVED-CL Input Interface
The PVED-CL provides:
•
•
Two 0-to-5 V DC analogue inputs
One CAN J1939 2.0b compatible bus
The CAN interface combines compact design, reliability and flexibility to offer the steering functionality
required. Additionally the CAN interface is used for configuration and diagnostic purposes.
For correct signal acquisition, read the requirements described in Analogue Interface, page 28 and PVEDCL Communication Protocol, 11025584.
Output Interface
The PVED:
•
•
•
Controls the physical movement of the main spool inside the valve
Controls the color of the LED
Transmits process data on CAN to help service personnel during installation and to verify the
Computational processed PVED-CL.
Battery
Likewise hydraulic power, sufficient electric power supply to the PVED-CL is crucial to operate the spool
inside the valve and to transport the control signals. Without it, the vehicle cannot be steered by the
PVED-CL. In order to cope with voltage fluctuations during cold engine start or disturbances by the
alternator, the PVED-CL incorporates a regulator to stabilize the voltage level used by the electronics and
sensors connected to the analogue inputs. The regulator makes the same PVED-CL compatible to both 12
and 24 Volt batteries. For more information, see Technical Data on page 24.
Actuator Position Sensor
The actuator sensor serves the purpose to allow external closed loop position control, for example soft
stop or variable steering sensitivity depending on cylinder position.
For added safety the PVED-CL provides connectivity of a second sensor inputs at the same interface type.
When position sensors are mounted on the steering actuator, the signal range must be at least 5 to 10%
larger than maximum physical movement of the actuator.
The PVED-CL incorporates a printed circuit board (PCB), LVDT sensor and a solenoid operated hydraulic
H-bridge. The PCB provides connectivity to CAN and analogue signals by two 4-pin connectors each
colored differently1 to distinguish CAN and power supply from cables with analog control signals. The
gray connector is dedicated for CAN and electric power supply and the black for connecting analogue
devices to the PVED.
1
Only for AMP. See also laser engraved text on PVED-CL to distinguish between CAN and Analog.
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PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
General Information
Functional Options Overview
Vehicle speed signal (J1939 CAN)
Mapping a Steering Device, page 27
and PVED-CL Communication
Protocol, 11025584
MMI
Display, Buttons e.g. to select program,
Display Info, Status, Diagnostic CAN
Configuration & Adjustment, page 14
and PVED-CL Communication Protocol,
11025584
PVED CL
Redundant Feedback
Analogue or CAN
Mapping a Steering
Device, page 33
High Priority
steering device
Analogue or CAN
Mapping a Steering
Device, page 33
Steering wheel sensor
(SASA) CAN
Mapping a Steering
Device, page 33
Control principle:
Closed loop
Page 60
Control principle:
Open loop
Page 42
Control principle:
Closed loop
Page 97
Control principle:
Open loop
Page 71
Low Priority
steering device
Analogue or CAN
Mapping a Steering
Device, page 33
Control principle:
Closed loop
Page 114
Control principle:
Open loop
Page 97
Vehicle Speed
Dependent Sensitivity
Page 55 / 62
Vehicle Speed
Dependent Sensitivity
Page 76
Vehicle Speed
Dependent Sensitivity
Page 101
Actuator Dependent
Sensitivity
Page 46
Actuator Dependent
Sensitivity
Page 75
Actuator Dependent
Sensitivity
Page 100
Anti-Drift
(knob position control)
Page 68
Soft End Stop
Page 85
Soft End Stop
Page 110
Soft End Stop
Page 55
Anti Jerk
Fixed Ramps
Page 78
Anti Jerk
Fixed Ramps
Page 103
Anti Jerk
Fixed Ramps
Page 48
Anti Jerk
Speed Dependent Times
Page 49
14
Feedback Sensor
Analogue or CAN
Mapping a Steering
Device, page 33
11025583 • Rev CA • 11 Jan 2010
Anti Jerk
Speed Dependent Times
Page 79
Anti Jerk
Speed Dependent Times
Page 104
High Priority set-point
controller (GPS)
ISO11798 CAN
Mapping a Steering
Device, page 33
Control principle:
Closed loop
Page 114
Vehicle Speed
Dependent Sensitivity
Page 125
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Safety Considerations
Safety Considerations
The steering architecture shall be designed with care. Controlling an EHPS or EH valve with a PVED-CL is
designed for off-road use only. More single channels of control may be identified in the architecture,
meaning that a single failure may have an impact on the steering behavior which cannot be resolved by
the architecture itself.
In these situations the driver or external equipment must intervene to bring the steering system to a safe
state.
The PVED-CL has on-board fault monitoring on the sensor interface as well as other critical parts of the
system. Please refer to Diagnostic & Troubleshooting on page 114 for an overview of the PVED-CL fault
monitoring.
On-road Operation
W Warning
The PVED-CL shall be de-energized while driving on-road. It is the OEMs responsibility to establish the
necessary means to inform and de-energize the PVED-CL from the cabin when driving on public roads.
Vehicle Speed Sensor
The vehicle speed sensor may be used to modulate the steering valves output as a function of vehicle
speed. However, the PVED-CL has no means to validate the validity of the vehicle speed signal as long as
the messages arrive correctly and the data field is within the valid range. Therefore:
W Warning
It is the OEMs responsibility to establish a reliable vehicle speed signal to the PVED-CL.
The provider of the vehicle speed signal shall implement means to detect faults and let the vehicle speed
sensor go silent if a fault is detected. A silent vehicle speed sensor will be detected by the PVED-CL and it
will enter fault state or optionally reduced state.
Closed-loop Operation
The PVED-CL may be used in closed-loop applications such as auto-guidance or row guidance. The PVEDCL has no means to validate the validity of an input steered wheel angle set-point or steered wheel
position as long as the set-point conform to the timing and data range requirements. Therefore:
W Warning
It is the OEMs responsibility to establish a reliable steered wheel angle set-point to the PVED-CL.
Analogue Input Sensors (Joystick or Wheel Angle Sensor)
The PVED-CL has no means to validate the validity of an input if the voltage conforms to range
requirements.
Any undetected faults may be resolved by changing to steering wheel steering.
W Warning
It is the OEMs responsibility to establish reliable analogue signal connections to the PVED-CL.
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Safety Considerations
Risk assessment
W
Warning
It is the OEMs responsibility to perform a hazard and risk analysis of the complete steering system and
add the necessary risk-reducing measures.
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Configuration and Adjustment
Configuration and Adjustment
The PVED-CL contains parameters to tailor the valve and PVED-CL to the vehicle and to provide the
required functionality. The OEM must be in possession of an interface device that is capable of reading
and transmitting messages on the CAN bus. It is recommended to implement the PVED-CL
communication protocol in a service tool or MMI.
Parameter Tuning Process
A typical parameter tuning process is:
CUSTOMER
Order prototype
Basic info on:
- Valve type & size
- Steering devices
- Sensors
- Vehicle data
- Desired functionality
Prototyping, testing
& parameter fine
tuning
Send order &
tuned parameter
set
SAUER-DANFOSS
Tune parameters,
Manufacturing &
Ship prototype
Running
production with
customized
parameters
Danfoss Technical Sales is able to ship steering valve prototypes that are vehicle install-ready and where
the relevant parameters have already been tuned towards their optimum values. The OEM customer
needs to do the fine-tuning.
Changing Default Parameters
The PVED-CL is manufactured with a parameter set that provides basic functionality for the steering
devices that are used. In most cases the default values need to be changed to adapt the valve to the
system.
Configuration of the PVED-CL is required to customize the EHPS/EH system to a particular vehicle.
Parameters are used to e.g. map steering devices and sensors, compensate for non-linearity in steering
signals and to control the functionality features in the PVED-CL.
There exists three different kinds of parameter types:
System Parameters
System parameters are parameters which describe:
•
•
•
•
PVED-CL interface & environment configuration (sensors, valves)
Start-up default behavior (sensor interface)
Addresses on J1939 CAN bus (customization of CAN IDs)
System identification information (valve type, software version, sales order number, PVED-CL serial
number)
It is vital in order to achieve correct PVED-CL functionality, that the system parameters are set correctly.
Some system parameters are used by the software to calculate the correct hydraulic gain, determining
left and right direction etc. An overview of all system parameters can be found in appendix System
Parameters on page 120.
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Configuration and Adjustment
Steering Device Parameters
Steering device parameters are parameters which define functionality related to a particular steering
device. These parameters will be common to a particular device at all times during operation and for all
steering device programs. The parameters define functionality as:
•
•
•
•
•
Detection criteria for steering device activation
Steering device closed-loop proportional gain
Spool control in the valve dead-band region
Program transition criteria for a steering device
Magnetic bridge enable/disable control for a steering device
An overview of all steering device parameters can be found in appendix Steering Device Parameters on
page 126.
Program Parameters
A number of user programs are available to each steering device. This enables programming flexible
functionality for each steering device such as:
•
•
•
•
Possibility to adapt the steering system to the working situation.
Personalized steering behavior (novice or expert level)
Customized/variable steering ratio/gain settings
Invert flow direction for e.g. backward steering
A number of programs are allocated to each steering device as shown in the table below. Each program
has a unique number which is used for requesting a new program from the MMI.
Number of programs per steering device
Steering device
Number of programs
Program number
Steering wheel sensor (SASA)
10
0-9
High priority steering device
5
20-24
Low priority steering device
5
25-29
High priority set-point controller
5
30-34
Example on program layout for high priority steering device
Set -point
to
Flow command
Ramp Limitation
Cushion stop
Program sub-sets
flow command
to
spool position
Active program for high
priority steering device
Program selection
Program page
Program=24
Program=23
Program=22
Program=21
Program=20
At power-up, the lowest program number for each device is applied i.e. program 0 for steering wheel
sensor, program 20 for high priority steering device etc.
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The program for a steering device becomes active as soon as the steering device is activated i.e. meets
the set-up criteria for when the PVED-CL shall regard a steering device as ‘being used for steering’.
An overview of all program parameters can be found in appendix Program Parameters on page 124.
Indexing Parameter
Each parameter has a unique index. Only one parameter can be accessed at a time. The system parameter
and steering device parameter indices are explicit and can be found in Appendix on page 120.
The program parameters are organized in a matrix. Each program parameter index for given program
and for a given steering device can be derived as follows:
Parameter index = [Steering Device number][Program index][Program parameter sub-index]
Number of programs per steering device
Steering device
Steering Device Number
Program Index
Steering wheel sensor (SASA)
1
0-9
High priority steering device
3
0-4
Low priority steering device
4
0-4
High priority set-point controller
5
0-4
The program parameter sub-index is the two last digits in program parameters in appendix Program
Parameters on page 124.
What is the program parameter index for ‘Steering sensitivity selector, Sse’ for the steering wheel
program 4?
Sse
Steering wheel device is defined as device number 1. The index for program number 4 is derived by
substituting x with 4 i.e. the index is 1409.
Sse for high priority steering device program 1 is 3109 etc.
Default program index for steering devices is 0.
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Configuration and Adjustment
Reading and Writing Parameters
Configuring the PVED-CL by means of setting parameters and reading parameters is done via a J1939
CAN bus, using proprietary PGN 61184. The configuration command set is described in PVED-CL
Communication Protocol, 11025584.
The following steps are needed to change a parameter:
Variable
Description
Power up PVED-CL
The PVED-CL shall be in operational, reduced or calibration mode (observe current mode in OperationStatus message)
to accept parameter changes.
Configure
On reception of one or more SetParameter messages, the contents are decoded and temporarily stored in RAM. The
PVED-CL will send SetParameterResponse to verify the reception of each command. Switching off the electric power to
the PVED before committing the data will erase all parameter changes.
Attempts to write or read non-existing parameters have no effect.
Commit to EEPROM
On reception of a single CommitData message, all RAM parameters are stored in EEPROM. During this operation, all
parameters are range checked. The commit procedure (copying data from RAM to EEPROM) will take 4 seconds to
complete. Committed parameters will first have any effect after the next boot up. If power is disconnected before all
parameters are stored in EEPROM, the PVED will power-up with the previous set of valid parameters. Observe
CommitDataResponse for information on commit process and success rate.
Program Transition Control
The PVED-CL can change steering program and thus steering behavior maximum 50 ms after reception of
a Select Program command. However, before a new program is applied, the PVED-CL validates the
system state for safe program transition.
System State
The system state is defined by:
Variable
Vehicle speed
Description
The vehicle shall drive slower or equal to a threshold value. The PVED-CL provides max
vehicle speed thresholds for each steering device.
The default values are chosen for robustness reasons to create a region rather than a
point.
Device
Steering by steering wheel
Index Default Value range
127
50
0-1000
(0.0-1000 km/h)
Steering by high priority steering device
327
Steering by low priority steering device
427
Steering by GPS, Laser or row guidance controllers 527
50
50
50
0-1000
0-1000
0-1000
The setting the treshold higher than the max. vehicle speed disable this condition.
Steering actuator
speed
Steering actuator
position
The spool inside the valve must be in or near its neutral position.
parameter.
Select Program/Program Transition
The program is applied when all conditions are met, otherwise it is rejected and the current program is
kept.
A program transition request is accomplished by transmitting a SelectProgram command (see
SelectProgram in PVED-CL Communication Protocol, 11025584).
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Configuration and Adjustment
Program Transition Acknowledge
Upon the reception of a SelectProgram command and if the system state allows it, the program
transition is executed and a SelectProgram response is transmitted (see SelectProgramResponse in
PVED-CL Communication Protocol, 11025584).
The currently active program is continuously transmitted in the PVED-CL operation status message (see
OperationStatus in PVED-CL Communication Protocol, 11025584).
How does the PVED work?
The PVED incorporates a printed circuit board (PCB), LVDT sensor and a solenoid operated hydraulic Hbridge. The PCB provides connectivity to CAN and analogue signals by two 4-pin connectors each
colored differently to distinguish CAN and power supply from cables with analog control signals. When
using AMP the gray connector is dedicated for CAN and electric power supply and the black for
connecting analogue devices to the PVED. Deutsch connectors are not-keyed, but PVED-CL is lasermarked with description.
The 4-pin AMP (Junior Power Timer) has been designed especially for the
automotive industries where high reliability and safety is required.
The features of the AMP connectors are:
AMP-connector
(Black)
A D2
G ND
5 Vout
AD1
CAN_H
G ND
V-bat
CAN_L
AMP-connector
(Gray)
•• Separate insulation of each lead ensures minimum risk of short cutting
••
••
••
••
Safe JPT locking
Safe locking of housing
Mechanical coding of housing
IP 66
AMP connectors
••
which prevents mistakes during installation
•• Easy disassembly
Electronic ControllerUnit
T
Contour of
PVG 32 casting
Neutral spring
CL
CR
LVDT
T
P
T
P (12bar+T)
P005 092E
Electronic Control Unit
The Electronic Control Unit (ECU) performs the following tasks:
•
•
•
•
•
CAN messages. The PVED hardware is compatible to CAN 2.0B
Converting two analogue input voltages between 0 and 5V to digital signals (10 bit)
Executing the steering software & monitoring for discrepancies with fixed time intervals
Output the main spool position setpoint
Controlling the LED color
Solenoid Valve Bridge
The PVED-CL features an integrated feedback transducer that measures spool movement in relation to
the input signal from the main micro controller, and by means of a solenoid valve bridge, controls the
direction, velocity, and position of the main spool of the valve. The integrated electronics compensate for
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Configuration and Adjustment
flow forces on the spool, internal leakage, changes in oil viscosity, pilot pressure, etc. This results in lower
hysteresis and better resolution.
Control Principle
In principle the input signal (set-point signal) determines the level of pilot pressure, which moves the
main spool. The position of the main spool is sensed in the LVDT transducer, which generates an electric
feedback signal registered by the electronics. The variation between the set-point signal and feedback
signal activates the solenoid valves. The solenoid valves are actuated so that hydraulic pressure drives the
main spool into the correct position.
Set point
Solenoid
valve bridge
Feedback signal
Spool or piston
Spool pos.
Transducer
Inductive Transducer, LVDT (Linear Variable Differential Transformer)
When the main spool is moved, a voltage, proportional to the spool position, is induced. The use of LVDT
gives contact less monitoring of the main spool position. This means an extra long working life and no
limitation as regards the type of hydraulic fluid used. In addition, LVDT gives a precise position signal of
high resolution.
Integrated Pulse Width Modulation
Positioning of the main spool in the PVED-CL is based on the pulse width modulation principle.
LED
A three-color LED on the top of the PVED provides high-dependable information of 4 basic states of the
electronic hardware.
Inactive: No electric power
Green: The PVED controls the spool movement inside the valve.
Yellow: The magnetic valves are temporary disabled due to the power saving feature or until the PVED is
operated. The magnetic valves can also permanently be disabled due to a major fault in the PVED or
wrong signal reception. The CAN bus communication is still operational for diagnostics according to
protocol definition. The spool position control is disabled.
Red: The PVED has detected a critical fault or inconsistency and has executed a “failed silent” procedure.
The spool position controller (Magnetic valves) is disabled. CAN is disabled for diagnostics.
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LED
In case the LED indicates yellow, details of the fault can be retrieved from the persistent error buffer and
transmitted on CAN. For more information on this topic see Diagnostic & Troubleshooting on page 114.
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Technical Specification
Technical Data
Technical Data
Electrical
Unit
Min
Max
Required supply voltage
V DC
11
32
Required current with magnetic valves enabled
A
1
0.3
Required current with magnetic valves disabled
A
0.1
0.03
Power consumption
W
7
10
Power consumption (magnetic valves off)
W
max 0.3
Viscosity
Cst
21
Contamination level (ISO 4406)
-
21/19/16
Max EMC
V/m
max 100
Oil temperature
ºC
-30
90
Recommended oil temperature
ºC
30
60
Ambient Temperature
ºC
-30
60
Pilot flow with magnetic valves disabled
l/min
0.2
0.4
Pilot flow with magnetic valves enabled
l/min
0.2
1.1
Pilot pressure to PVED
bar
10
15
Stabilized voltage supply
V DC
4.80
5.20
Max current taken from stabilized voltage supply
mA
100
Digital conversion of signals at AD1 & 2
V DC
0 to 5 VDC into 0 – 1023 (10 bit)
Available baud rates to CAN
Kilo bit/s
125, 250, 500
Hydraulic
460
Signals
AD1 & 2 input impedance
Approximately 1MOhm
Max analogue signal source impedance
<100 kOhm
Protection
Grade of enclosure (IEC 529) Connector
IP
66
Over voltage at 36 V DC
minutes
5
Reverse polarity
minutes
Infinite for all faults except: see Installation on page 25.
Spool position Hysteresis in % of full spool stroke
-
0.5
1
Inherent Ramp-up time from neutral to full open
ms
50
210
Inherent Ramp-down time from full open to neutral
ms
40
150
Boot time EHPS software
ms
1200
1500
Recognition time of incorrect voltage signals
ms
50
Recognition time of incorrect supply voltage
ms
200
Recognition time of incorrect CAN signals
ms
200
Recognition time of incorrect internal operations
ms
50 (watchdog)
Performance
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Installation
Installation
Connector Interface
Two connector variants are available: Deutsch and AMP. Interchanging the Deutsch connectors will not
destroy the PVED-CL however the PVED-CL will not work.
Analog sensors
Switch
Uninterruptable
power source
CAN bus
sensors
CAN-L - 1
1 - AD1
Vbat+ - 2
2 - 5V out
Vbat- - 3
3 - GND
CAN-H - 4
Grey connector
4 - AD2
Black connector
P005 095E
The CAN-wiring is done according to J1939-15, where as Analogue wiring is recommended to be at least
0.75 mm2 and no longer than 9 meters.
W
Warning
The following wiring faults will destroy the PVED-CL ‘5V out’ output:
•
•
•
Connecting GND to 5V out AND Vbat+ to VbatConnecting Vbat+ to 5V out
Short-circuit 5V out to GND for more than 5 minutes
Valve Interface
The PVED-CL shall always be calibrated to the valve it is controlling. Valve calibration enables interfacing
to various valve types as well as cancellation of mechanical, electrical and environmental dependent
tolerances which can lead to performance degradations. Valve calibration is normally only needed once
at production time, at installation time, in a PVED-CL replacement situation or in performance fine-tuning
situations.
The PVED-CL is calibrated to the valve by a dedicated valve transfer function, having 7 parameters to
compensate for discontinuities (hydraulic dead-band), asymmetry (maximum flow) and non-linearity in
the left and right spool characteristic. Correct parameter values are essential for achieving optimum
performance in all PVED-CL operation modes.
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Installation
Valve calibration objectives
The PVED-CL calibration shall satisfy multiple conflicting objectives. Like for any proportional spool valve,
the purpose of the hydraulic dead-band is to prevent unwanted oil output flow while the main spool is
resting in neutral position.
In PVED-CL steering wheel mode (open-loop application), the dead-band prevents noise (electrical and
mechanically), from e.g. the steering wheel sensor (SASA), from leading to unwanted oil output flow or
creating small steady-state quivering wheel movements. On the other hand, a too large dead-band may
result in a noticeable steering wheel dead-band which may not be desirable.
For closed-loop applications such as auto-steering, the hydraulic dead-band has an undesirable effect.
Small position control errors are corrected by proportional spool activations to output a correcting flow.
However, if the spool movement is inside the hydraulic-dead-band, then a steady-state error is present
which will cause the vehicle to drift from the desired course. This is one of most likely reason for
degraded auto-steering performance and shall be avoided.
The performance objective in closed-loop mode is to always output a flow when a steered wheel position
error is present while ensuring that the valve operation is not to crude, leading to jerky vehicle course
corrections.
Dead-band crossing
In open-loop operation mode, the spool operation in the hydraulic dead-band can be configured by
parameters. The spool can either be controlled through the hydraulic dead-band manually by following
the input device set-point. This allows the user to control the level of pressure built-up of the steered
wheels. This is controlled with the valve-specific parameters, as well as the steering device specific
parameters (See the input device specific chapters).
Alternatively the spool operation can be configured to ‘jump’ between over the dead-band. This
resembles servo valve operation and gives a fast steering response.
In PVED-CL closed-loop operation mode, the spool will always jump over the hydraulic dead-band.
Valve types overview
The below table shows the hydraulic dead-band characteristics and tolerances for the available steering
valves. Due to mechanical tolerances on the valve parts, the exact hydraulic dead-band position cannot
be predicted for any single valve. Similarly, it may differ from valve to valve.
Steering valve tolerance characteristics
Valve type
Nominal dead-band
Dead-band tolerance
Maximum spool displacement
[mm]
[Xsp]
[mm]
[Xsp]
[mm]
[Xsp]
EH, dynamic spool
0.5
94
0.36 – 0.62
77 – 108
3
430
EH, static spool
0.8
136
0.6 – 1.1
106 – 177
3
430
OSPEH
0.8
136
0.6 – 1.1
106 – 177
4
560
EHPS
1.3
204
1.05 – 1.55
170 - 238
7
915
Xsp values are valid for programmed linear spool characteristic.
Valve transfer function
The valve transfer function matches the PVED-CL to the valve and thus also the hydraulic dead-band. The
PVED-CL converts the calculated requested port flow to a spool set-point, Xsp. Xsp is a scaled
representation of the physical spool displacement where 0 is neutral position and ±1000 is the maximum
possible spool stroke.
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Diagram
Flow, Q
[L/min]
Maximum flow (Vcap)
Xspl_1000
Lspl
Xspr_1000
Lspr
0
0
Closed-loop mode
(Xspl_0 - XspClosedLoopOffset)
(Xspr_0 + XspClosedLoopOffset)
Open-loop mode
Xspl_0
Flow range
L
0
Spool displacement
[mm, Xsp]
Xspr_0
hydraulic deadband
R
Flow range
Valve interface parameters
Xspl_0 Left software dead-band in PVED-CL open-loop operation mode.
Lspl Controls the left spool position-to-flow linearity. Use for compensating for non-linearity or to create
non-linear spool characteristics. Default is linear spool characteristic.
Xspl_1000 Left maximum port flow. Port flow at this set-point is equivalent to maximum valve capacity.
Xspr_0 Right software dead-band in PVED-CL open-loop operation mode.
Lspr Controls the right spool position-to-flow linearity. Use for compensating for non-linearity or to
create non-linear spool characteristics. Default is linear spool characteristic.
Xspr_1000 Right maximum port flow. Port flow at this set-point is equivalent to maximum valve
capacity.
Vcap Parameter holding information about the maximum flow capacity of the valve.
ClosedLoopXspOffset Spool position offset which is added to spool position set-point in closed-loop
mode only. The offset ensures that the spool is always operated at a point where the valve outputs a flow.
The offset extends the software open-loop dead-bands to form closed-loop dead-bands as illustrated
above.
Valve interface parameters
Symbol
Index
Default
Value range
Xspl_0
737
-185
-250 to 0 for EH valve
-350 to 0 for EHPS valve
Lspl
702
0
-10 to 10 (max regressive to max progressive)
Xspl_1000
729
-1000
-1000 to -300 for EH valve
-1000 to -400 for EHPS valve
Xspr_0
738
185
0 to 250 for EH valve
0 to 350 for EHPS valve
Lspr
703
0
-10 to 10 (max regressive to max progressive)
Xspr_1000
747
1000
300 to 1000 for EH valve
400 to 1000 for EHPS valve
Vcap
706
25
5 to 120 (5 to 120 L/min)
ClosedLoopXspOffset
748
25
0 to 1000 (0 to ±maximum spool stroke)
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Valve interface parameters (continued)
Symbol
Index
Default
Value range
ValveType
65121
1
1 - EHPS valve
2 - EH/OSPE valve
Note that the default values may not be suitable for all valve types.
Valve calibration methods
The PVED-CL can be calibrated to a valve in three possible ways:
•
•
•
Use conservative software dead-band values
Manual software dead-band calibration
Valve auto-calibration
Method 1: Conservative software dead-band values
This method does not require any specific sensor or measurement equipment. The principle in this
method is to set the open-loop and closed-loop software dead-bands sufficiently low and high,
respectively, and let these dead-bands be valid for an entire series of valve units.
1. The open-loop dead-bands are determined based on the minimum hydraulic dead-band tolerances
for a particular valve.
2. The closed loop dead-bands are determined by setting the ClosedLoopXspOffset parameter, based
on knowledge to the maximum hydraulic dead-band tolerances for a particular valve and adding
some margin, to always have a correcting flow available.
Example: Determine the general software dead-bands for a series of PVED-CL / EH valve with a
dynamic spool:
•
•
•
•
•
•
All dead-band values are in scaled spool position set-points, Xsp.
From the Valve types overview on page 26 we get the minimum hydraulic dead-band to 77 and a
maximum hydraulic dead-band equal to 108.
Xspl_0 and Xspr_0 are set to ±70 to have a small overlap (±7) to the minimum hydraulic dead-band.
To ensure enough flow for e.g. auto-steering, ClosedLoopXspOffset is set equal to the maximum
hydraulic dead-band plus a little margin to guarantee a flow.
In this example a margin equal 25 is chosen which result in a ClosedLoopXspOffset equal to (108 +
25) – 70 = 63.
Xspl_1000 and Xspr_1000 are set to 430 to operate the EH valve in its full range.
Using conservative dead-band values will create steering performance which will vary slightly from
valve to valve. E.g. for variable steering ratio applications, the dead-band and steering ratio will vary
slightly. Similarly in auto-steering mode, the flow for correcting the steered wheels may vary from
smooth corrections to more jerky corrections.
Method 2: Manual software dead-band calibration
The principle in this method is to match the PVED-CL software dead-bands to the hydraulic dead-band
for the particular valve it is controlling. This kind of calibration will reduce the impact of mechanical
tolerances and thus reduce the valve-to-valve performance differences.
This method does not require any specific sensor but requires a service tool to be connected to the PVEDCL. The operator performing the calibration must be able to observe a movement of the steering actuator
or steered wheels during the procedure and read out main spool set-points.
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For production, calibration and field service purposes, the PVED_CL allows direct control of the main
spool. On reception of a SetSpoolPosition message (see PVED-CL Communication Protocol, 11025584),
the main spool can be commanded to a specific set-point position. Manual software dead-band
calibration can only be performed when the PVED-CL is in calibration mode. See section
EnterCalibrationMode in PVED-CL Communication Protocol, 11025584 on how to run the PVED-CL in
calibration mode.
The procedure requires a service tool to set the PVED-CL in calibration mode and to control the main
spool set-point. The procedure is:
1. Find the hydraulic dead-band by gradually increasing the main spool set-point in small steps (5 – 10),
until steered wheel movement is observed. Must be done for both left and right direction.
2. Determine Xspl_0 and Xspr_0 by subtracting 10-25 from the detected hydraulic dead-bands. This
shall ensure that the open-loop dead-bands are inside the hydraulic dead-band with an over-lap.
3. The closed-loop dead-band values are calculated as the detected hydraulic dead-band values plus
some margin depending on the desired minimum correction flow. Typical values are 20-30 fur-ther
out than the hydraulic dead-band values.
4. Xspl_1000 and Xspr_1000 are set to the respective maximum stroke for the valve (see valves types
overview).
The applied values are example values. The optimum values are vehicle specific.
The result that can be achieved with manual calibration is also operator sensitive. Manual valve
calibration depends on visual confirmation of wheel movement. Differing perception of wheel
movement will affect the final steering performance.
Method 3: Valve auto-calibration
A third alternative is to utilize a build-in valve auto-calibration algorithm which can automate the valve
calibration and produce deterministic results. The algorithm utilizes the wheel angle sensor and can be
regarded as an automated manual calibration procedure.
See section StartValveAutoCalibration in PVED-CL Communication Protocol, 11025584 on how to
invoke the valve auto-calibration.
During the calibration procedure, the actuator position/steered wheel angle (Yact) change is measured in
a pre-defined time interval (dt) to derive a steering velocity representation. Exceeding a defined Yact/dt is
used as an “output flow detected” criterion. The principle in valve auto-calibration is to search for the
main spool set-point Xsp, where output flow is detected and then derive the software open-loop deadbands by applying a fixed rule . This is done for both left and right direction.
Preconditions:
1. The PVED to valve auto-calibration is available only when PVED is in the calibration mode. See section
EnterCalibrationMode in PVED-CL Communication Protocol, 11025584 on how to set the PVED-CL in
calibration mode.
2. The valve auto-calibration command shall be sent from the MMI controller.
3. A wheel angle sensor shall be installed, mapped and calibrated.
4. A steering wheel sensor (SASA) shall be installed and mapped.
5. The wheels shall be positioned in the straight ahead position ± 25% of the max angle in one direction
prior to invoking valve auto-calibration.
6. Auto-calibration shall be performed while the wheels are on an even and solid surface. No front load
or front attachment shall be mounted.
7. Parameter configuration is not possible during the auto-calibration procedures. Any attempt to read
or write parameters is ignored.
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Valve auto-calibration command parameters
See section StartValveAutoCalibration in PVED-CL Communication Protocol, 11025584 on how to
format the command and for detailed status/error code information.
Valve auto-calibration command parameters
Command
Description
XspStartSearch
Sets the starting main spool set-point. Values close to 0 will include more of the hydraulic dead-band in the search and thus
consume more time. Setting the value closer to a main spool position where flow is expected, will speed up the calibration
time.
The starting main spool set-point is used for both the left and right direction.
XspIncrementSize
The main spool set-point increment size defines the step that the algorithm is using in each iteration. As a consequence, it
defines the resolution of the calibration result. A small value < 5 could potentially produce a more accurate calibration result
at the expense of calibration time. However, repeatability of the calibration result may be poor. A step size > 5 will speed up
the calibration time at the expense of calibration accuracy.
YactDiffThreshold
Set the ‘change threshold’ for ‘steering actuator position’/‘steered wheel position’ (Yact) that is the criterion for detecting a
flow. The position change, ∆Yact, is measured in the time-out period for each main spool position set-point increment.
A low threshold (< 20) will detect very small flows but is sensitive to e.g. noise from the wheel angle sensor. Too low
thresholds will often result in false flow detection which again results in too conservative software dead-bands.
A high threshold (> 60) requires a significant position changes. Further-more, the calibration time increases because the
main spool needs to be increment to a higher set-point before the necessary output flow is present.
Yact is the scaled ‘steering actuator position’/‘steered wheel position’.
TimeOutPeriod
The time between two consecutive steps of the automatic calibration process and thus sets the measurement time in which
∆Yact is measured.
A value <500 could reduce the calibration time, but requires careful selec-tion of the YactDiffThreshold setting. A value
>1000 significantly in-creases the calibration time requirement.
XspCalibrationOffset - Main spool displacement offset which is subtracted from the detected spool setpoint which satisfies the ‘output flow detected’ criterion. Subtracting the offset from the detected spool
set-points results in the open-loop software dead-bands values.
XspCalibrationOffset is a parameter value and is used for both left and right spool direction.
XspCalibrationOffset parameters
Symbol
Index
Default
Value range
XspCalibrationOffset
758
25
0 -300 (scaled main spool set-points, Xsp)
XspCalibrationOffset is a parameter value and not intended to be modified on each auto-calibration
invocation.
Valve auto-calibration procedure
The valve calibration procedure and how all involved parameters are used, works as follows.
The procedure is showed for the right dead-band only.
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Steering actuator speed
Steered wheel angle speed
∆Yact/dt
2
YactDiffThreshold
XspStartSearch
1
0
Xspr_0
4
Xcal_r
3
Spool displacement
[Xsp]
5 Compensate Xspr_1000 value
1. The main spool set-point starts at XspStartSearch
•
•
•
∆Yact is calculated as the difference measured in TimeOutPeriod ms
Every TimeOutPeriod ms, the main spool set-point is incremented by XspIncrementSize
Step 1 is repeated until step 2 becomes valid
2. The measured ∆Yact exceeds YactDiffThreshold
3. The current Xsp is stored and denoted Xcal_r
4. The open-loop dead-band parameter is calculated as Xspr_0 = Xcal_r – XspCalibrationOffset
•
The Xspr_0 value is written to eeprom
5. The main spool set-point where the valve outputs it nominal maximum flow, Xspr_1000, (see Valve
transfer function) is adjusted equally to the Xspr_0 change. As an example; if the detected Xspr_0 has
shifted 10 Xsp steps towards neutral compared to the previous Xspr_0, then Xpsr_1000 is shifted 10
Xsp steps as well. This maintains the transfer function slope.
The same procedure is applied to the left dead-band. When both open-loop dead-bands are calculated
and written, the changes are automatically committed to eeprom. The progress through the valve autocalibration procedure can be monitored on the CAN bus.
Operating the steering wheel during valve auto-calibration will immediately abort the valve autocalibration process. The PVED-CL will remain in calibration mode until power is cycled.
Suggested valve auto-calibration command values
The following table shows the suggested valve auto-calibration command values for the different valve
types. Other settings may be more appropriate. The optimum parameters for a particular vehicle must be
found by experimentation and testing.
Suggested valve auto-calibration command values
Command parameter
EH dynamic
EH static
OSPEH
EHPS
XspStartSearch
35
50
50
130
XspIncrementSize
5
5
5
5-10
YactDiffThreshold
20
20
20
20-30
TimeOutPeriod
500
500
500
500-1000
Changing TimeOutPeriod will affect the criterion where a flow is detected. Fix the TimeOutPeriod to 500
ms or 1000 ms, and adjust YactDiffThreshold until
a repeatable and robust performance is obtained.
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Valve auto-calibration quick-guide
Valve auto-calibration procedure
1. Issue the start valve auto-calibration command from a MMI.
2. Monitor valve auto-calibration status messages. Optionally, enable status set 1 for detailed
monitoring of the analogue wheel angle sensor signal and the spool position set-point
3. Wait for status ‘auto-calibration completed’
See StartValveAutoCalibration and AutoCalibrationStatus in PVED-CL Communication Protocol,
11025584.
Parameter tuning order
1. Adjust XspCalibrationOffset. Use 65 as a starting reference.
2. Adjust and test valve auto-calibration command values (PVED-CL calibration mode)
See Suggested valve auto-calibration command values on page 31 for starting values.
3. Test and evaluate open-loop steering performance (operation mode)
4. Repeat step (1)2-3 until satisfactory results are obtained.
5. Adjust parameter ClosedLoopXspOffset. Use 65 as a starting reference.
6. Test and evaluate closed-loop steering performance (PVED-CL operation mode)
7. Repeat step 5-6 until satisfactory results are obtained.
The PVED-CL shall be powered-cycled after an auto-calibration before the new dead-band
parameters take effect.
The PVED-CL closed-loop performance can also be evaluated in calibration mode by issuing the
SetFlow command. To evaluate the smallest possible actuator speed, set ‘Requested Flow’ to ±1 and
apply ‘Closed-loop flow-to-spool-position scaling’. See SetFlow in PVED-CL Communication Protocol,
11025584.
Verification of auto-calibration result stability
Check that the calibration results can be reproduced repeatedly (10-20 times) for a specific set of autocalibration command values. The resulting parameters Xspr_0 and Xspl_0 should stay within
±XspIncrementSize.
If repeatability is poor, then adjust the auto-calibration command values. Typically, YactDiffThreshold and
XspCalibrationOffset are subject for tuning and needs to be increased.
Verification of the open-loop performance
Check that no unwanted steering actuator movement takes place while operating the PVED-CL in openloop mode for e.g. variable steering ratio or joystick applications. Verify that the steering actuator is not
quivering in a steady state and that the steered wheels are not moving aggressively for small steering
wheel or joystick inputs. Both situations indicate no or a too small hydraulic dead-band.
XspCalibrationOffset should be increased and auto-calibration is repeated.
Secondly, verify that the steering performance is symmetric in both directions i.e. that the steering
actuator moves with the same speed in both directions for the same steering input in both directions.
If asymmetry is evident then a new valve auto-calibration shall be performed.
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Verification of the closed-loop performance
Check that the desired steering accuracy can be obtained when using the PVED-CL in closed-loop mode
such as auto-steering. The vehicle shall follow the path within the expected precision with small steering
actuator movements.
If the vehicle cannot follow a path within the expected precision or deviates from the desired path, then
it may be due to a hydraulic dead-band. Increase ClosedLoopXspOffset in steps of 5-10 and test until the
performance is satisfactory.
If the steered wheels move aggressively and jerky while following a path in closed-loop mode, then the
valve outputs too much flow for small corrections and ClosedLoopXspOffset shall be decreased and
tested in steps of 5-10.
If there is a tendency that the vehicle deviates in only one direction in closed-loop mode, then one of the
open-loop dead-bands may not be correct and a new valve auto-calibration shall be performed.
Logging and monitoring
In addition to ValveAutoCalibrationStatus, PVED-CL status set 1 can also be enabled for detailed
monitoring and logging of the CAN bus traffic while the auto-calibration runs.
The below chart below shows the auto-calibration progress of an EH valve with a static main spool, fitted
to a 150 HP tractor. Values from Suggested valve auto-calibration command values on page 31 are used;
XspStartSearch 50, XspIncrementSize 5, YactDiffThreshold 20 and TimeOutPeriod 500.
The auto-calibration progress of an EH valve with a static main spool
Explanation:
At 12 second the steering actuator begins to move. Around 14 seconds the actuator speed has exceeded
YactDiffThreshold where after the algorithm proceeds to the left direction. At 26.5 seconds the actuator
speed exceeds YactDiffThreshold and the algorithms stores the dead-band parameters and terminates.
W
Warning
Check for misaligned maximum spool stroke set-point parameter values: Previous auto-calibration
attempts with faulty command values may have shifted the parameters Xspr_1000 and Xspl_1000 to
inappropriate values which may result in asymmetric flow characteristics. Ensure that Xspr_1000 and
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Xspl_1000 have values close the default values (±30) for the applied valve. See ‘Xsp maximum spool
displacement’ in table Valve types overview on page 26.
Check for severe noise levels from the analogue wheel angle sensor: The wheel angle sensor AD noise
shall not exceed ±4 counts when observed via Status set 1 (see Status in PVED-CL Communication
Protocol, 11025584). High noise levels will increase the likelihood of interpreting noise as steered wheel
movement. Furthermore, repeatability may be poor.
Mapping a Steering Device
All the above mentioned functionality must be ‘activated’ by mapping or ‘Setting Present’ the individual
steering devices. This means appropriate parameters must be set to the right values, as shown in the
table below. This is done as mentioned in Reading and Writing Parameters on page 20.
The default settings mean a PVED-CL with power on, a CAN Steering Wheel Sensor and an analogue
joystick physically connected, will not interpret any of these inputs until the mapping is done. CAN sensor
messages are ignored and so are the voltage-inputs on the AD pins.
Steering Device Signals
Index
Default
Mapping Set Value
Steering wheel angle signal (Priority 1)
65101
0
0 - not present
255 - present on CAN
High priority steering device (Priority 2)
65102
0
0 - not present
1 - present at AD1
2 - present at AD2
4 - present at CAN
Low priority steering device (Priority 3)
65103
0
0 - not present
1 - present at AD1
2 - present at AD2
4 - present at CAN
Primary steered wheel (or actuator) signal
65104
0
0 - not present
1 - present at AD1
2 - present at AD2
4 - present at CAN
High priority set-point controller (Priority 4)
65105
0
0 - not present
255 - present on CAN
Redundant steered wheel sensor signal
65107
0
0 - not present
255 - present on the same interface type
Vehicle speed signal
65108
0
0 - not present
255 - present on CAN
OSP signal
65109
0
0 - not present
255 - present hydraulically
When mapping the vehicle speed sensor, the CAN source address of the vehicle speed sensor shall be
configured correspondingly in the VehicleSpeedSensorSourceAddress parameter. See System
Parameters on page 120.
Only one signal per analogue channel can be acquired
Mapping the OSP signal serves only the purpose to monitor the PVED for conflicting setpoints when
steering by steering wheel using the EHPS valve with hydraulic back up. Other parameter conflicts are
mentioned appendix Program Parameters on page 124.
A mapped device can be de-activated by means of sending a DeviceDisableCommand as mentioned in
chapters High Priority Steering Device Enable/Disable Control on page 83 and Low Priority Steering Device
Enable/Disable Control on page 103.
The High priority set-point controller can similarly be de-activated. Please refer to PVED-CL
Communication Protocol, 11025584.
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Analogue Interface
A 200 Hz first-order low-pass filter is applied before the AD sampling. Both analogue voltage signals at
AD1 and AD2 are converted into a digital value between 0 and 1023 [AD full scale]. A running average
filter, which takes 5 consecutive samples per 5 ms, removes high frequent noise. In case a redundant
steered wheel angle sensor occupies both analogue inputs, comparison between both scaled values is
made.
Block diagram of processing analogue to digital converted signals
Init
Analogue signal
range: 0 to 5 V DC
Pre-filter
(low pass)
200 Hz
1000 Hz
sampler
10-bit
A/D
Pull down resistor
Running average
filter:
N = 5, dt = 1ms
200 Hz
sampler
Raw analog to digital
converted signals
range: 0 to 1023
P005 222E
AD Signal Interface Requirements
When control signals are mapped to pin AD1 or AD2, the sampled voltage is range-checked to be
between 20 and 967 [AD full scale]. These bounds are used for detecting the signal being shortcut to
ground or VCC/battery power supply.
Voltage signals must always be in range in order not to trigger the signal validation monitor which results
in PVED fault state or reduced state. The maximum input range which leaves margin for noise etc. is 30 to
957 [AD full scale]. As a rule of thumb, one should attempt to have 0.5 V and 4.5 V at the end-stops and
approximately 2.5 V at neutral. The parameter defaults are set-up to this voltage range. A weak internal
pull-down resistor will pull the input below the fault detection threshold if the input is open-circuited.
The AD input impedance is > 1 MΩ.
Scaling Analogue Signals
The sampled analogue values needs to be scaled to the internal calculation domain before the signals
can be applied in the software control algorithms. Scaling is a method to fully utilize the software
calculation dynamic by assigning fixed calculation domain values to the equivalent analogue values for
maximum left, right and neutral and even intermediate values if desired. Scaling is done by sample value
to calculation domain transfer characteristics. Two different transfer characteristics are available for each
AD input.
Linear Transfer Characteristic (3-Point)
Linear transfer characteristic is suitable for sensors with a known characteristic such as joysticks and miniwheels. The transfer characteristic orientation depends on the sensor mounting orientation (both cases
are shown below).
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Sampled AD value
AD1(2)_1000_Left
AD1(2)_1000_Right
Max left = 800
Neutral = 440
Max right = 75
Max left = 30
Neutral = 500
Max right = 957
-1000
AD1(2)_Neutral
1000
Scaled value
AD1(2)_1000_Right
AD1(2)_1000_Left
0
Margin
Short-circuit
Symbol
Index
Default
Value range
AD1_1000_Left
65080
100
[30;957]
AD1_Neutral
65086
500
AD1_1000_Right
65083
900
AD1_Linear
65087
255
0 (Non-linear), 255 (Linear)
AD2_1000_Left
65089
100
[30;957]
AD2_Neutral
65095
500
AD2_1000_Right
65092
900
AD2_Linear
65096
255
•
•
0 (Non-linear), 255 (Linear)
When building a transfer characteristic, the characteristic shall be monotonically increasing or
decreasing. An attempt to build illegal characteristics is not possible.
AD values for Neutral shall be between the AD values for left and right.
Non-Linear Transfer Characteristic (5-Point)
A non-linear transfer characteristic is suitable in situations where a sensor output is non-linear due to e.g.
sensor mounting geometry.
Scenario
Applying a linear transfer characteristic (3-point) to a non-linear steered wheel angle sensor in a closedloop application (auto-guidance or GPS) may result in incorrect steered wheel positions for set-points not
equal to neutral or the end-positions. Furthermore, the steered wheel angle may not be symmetrical
around neutral. The effect of non-linearity may become apparent in auto-steering applications where a
vehicle shall drive in precise circles.
In general, it is recommended to have “an as linear as possible” relation between the steered wheel angle
and the steered wheel angle sensor. This can be achieved by clever mechanical sensor mounting.
However, it may not always be possible to achieve linearity mechanically. To electronically compensate
for a non-linear sensor characteristic, two extra points are included in the calibration.
The two extra points represents the steered wheel angle, where the steered wheel is precisely in between
neutral and right or left end-stop respectively.
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Sampled AD value
AD1(2)_1000_Left
AD1(2)_1000_Right
AD1(2)_500_Right
AD1(2)_500_Left
-1000
AD1(2)_Neutral
1000
Scaled value
AD1(2)_500_Left
AD1(2)_500_Right
AD1(2)_1000_Right
AD1(2)_1000_Left
0
Margin
Short-circuit
Symbol
Index
Default
Value range
AD1_1000_Left
65080
100
[30;957]
AD1_500_Left
65055
300
AD1_Neutral
65086
500
AD1_500_Right
65062
700
AD1_1000_Right
65083
900
AD1_Linear
65087
0
0 (Non-linear), 255 (Linear)
AD2_1000_Left
65089
100
[30;957]
AD2_500_Left
65069
300
AD2_Neutral
65095
500
AD2_500_Right
65076
700
AD2_1000_Right
65092
900
AD2_Linear
65096
0
•
•
0 (Non-linear), 255 (Linear)
When building a transfer characteristic, the characteristic shall be monotonically increasing or
decreasing. An attempt to build illegal characteristics is not possible.
AD values for Neutral shall be between the AD values for left and right.
Steering Actuator Position Signal
The steering actuator position signal can be mapped to either AD1 or AD2. Scaling parameters Max left
and Max right are set respectively equal to the digital converted voltage at the left and right end-lock
position. The third parameter “Middle” is normally set equal to the digital converted voltage when the
steering actuator is set in the straight forward driving position.
The default values meet most analogue sensors with standard 0.5 to 4.5 signal span.
Analogue Input Drift Compensation
A radiometric compensation algorithm has been implemented to ensure robustness of the checks even
in situations where the Vext-supply voltage fluctuates from 4.80 to 5.20 V DC. Range checking is done on
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Installation
the compensated value. Compensation is only required for analogue sensors without built-in
compensation - hence sensors whose output is directly depending on the Vext-supply supply voltage.
The objective is to reduce the risk of drift in calibration value as a result of aging or temperature of the
electronic circuits. To select compensation in PVED-CL or not, use parameter
AnalogChannelCompensation.
Compensation can be applied to either input or both of them.
Symbol
Index
Default
Value range
AnalogChannelCompensation
65098
0
0=None, 1=AD1, 2=AD2, 3=Both AD1 and AD2
Transmitting the Voltage Readings on CAN
In order to calibrate the AD inputs from steering devices or steering actuator position signals, the read AD
value shall be echoed back to user via the CAN bus.
Sending a StartStopStatus status set 1 message will invoke the PVED-CL to send out a status message
with data [AD1][AD2][AD3][Xsp]. AD1 and AD2 are the analogue PVED-CL interface ports. AD3 is the
spool position reading. Xsp is the spool set-point calculated by the PVED-CL.
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Steering Device Transition
Steering Device Transition
The PVED-CL allows steering with electric signals from more than one steering device. Every 50 ms, the
PVED sequentially monitors all mapped steering device signals according to their priority.
It selects one of steering devices based on:
•
•
the amount of signal change detected in the steering signal per time unit and
the current in System State on page 20. When the steering signal change per time unit exceeds a userdefined threshold, it is considered as a request to steer the vehicle with that particular steering
device.
The system state is used to ensure:
Smooth transition from one to another device by requiring the valve spool to be inside or near the
valve dead-band.
Reach-ability of the closed-loop control by demanding the steering actuator to be within the control
region of the closed-loop controller (if closed-loop control is applied).
Safe transition to a steering device, and hence program by only allowing this change at vehicle
speeds equal to or lower than the threshold value defined in Program Transition Control on page 20
provided that a vehicle speed signal is present.
•
•
•
When all above criteria are fulfilled, the steering device is selected and the associated steering control
principle is applied. If no steering device fulfils the criteria the previous selected device remains. On
power up, all devices are normally in their rest position, which means that no device is selected. The
magnetic valve is disabled while no device is selected.
Threshold Definition
To determine if a steering device exceeds its defined threshold, two parameters shall be defined for each
applied steering device namely the maximum steering motion speed and the steering motion threshold.
The threshold is defined as a percentage of the maximum steering motion speed.
Define the Maximum Steering Motion Speed
The fastest steering input is defined as the time in ms to change the input signal from its minimum to its
maximum value or visa versa, hence the value corresponding to 100%. This means e.g. the minimum time
required to make one full turn for the steering wheel, one full movement left to right on the joystick, etc.
CAN
AD
Volt
4095
900
4.5
0
100
0.5
t2
t1
time
Example: How the maximum signal change is carried out
Device
Index
Default
Value range
Steering by steering wheel
111
500
500 – 750 (120 to 80 rpm)
Steering by High priority steering device
311
200
150 – 450
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Steering Device Transition
Example: How the maximum signal change is carried out (continued)
Device
Index
Default
Value range
Steering by Low priority steering device
411
200
150 – 450
Steering by High priority external set-point controller
511
200
10 – 2000
Changes to parameters of non-present steering devices have no effect.
Define the Steering Motion Threshold
The steering motion threshold represents a percentage of the maximum steering motion which is
defined for each steering device. This means for the PVED-CL to detect a steering request on a new
steering device, the input on this device shall happen faster than the defined threshold speed.
The default values are a compromise between a quick respond to steering inputs and avoiding
unintentional transitions due to noise that might be present in the steering signal.
Device
Index
Default
Value range
Steering by steering wheel
119
50
0 – 200 (0.00 to 20.0 % of max.
activation speed)
Steering by High priority steering device
319
100
0 - 200
Steering by Low priority steering device
419
100
0 - 200
Steering by High priority external set-point controller
519
100
0 - 200
Changes to parameters of non-present steering devices have no effect.
Thresholds equal to zero auto-selects the device whenever a device of higher priority enters the non-active state.
Thresholds near zero could cause unintentionally transitions due to noise in the input signals.
No priority is given to higher priority devices when steering within the non-active operation state.
Once a steering device has been selected for steering it will be active until another steering device meets
the criteria for being selected for steering.
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Steering Wheel Sensor Noise Gate
Retrieving Steering Device Information
The PVED-CL continuously transmits status information on which steering devices is mapped in the
system and their present state. Refer to OperationStatus in PVED-CL Communication Protocol, 11025584.
Steering Wheel Sensor Noise Gate
Noise from the SASA sensor may be a result from sampling noise on the least significant bits or
mechanical vibrations causing small steering wheel movements. Regardless of the cause, the noise in the
SASA message data may propagate though the PVED-CL and show itself as small pressure build-ups or
small wheel movements. This high SASA sensitivity is desired for high controllability and good response
to slow steering wheel movements whereas it is less desired when the steering wheel is not activated.
A compromise can be achieved by setting up the steering wheel sensor noise gate to filter out small
steering wheel data changes after some specified time with no steering wheel activation.
StwDxFilterThreshold parameter defines the steering wheel angle over time threshold, where a ‘no
steering wheel activation’ confidence timer is incremented. Any steering wheel activation which results
in a steering wheel angle/dt higher than StwDxFilterThreshold will reset the timer.
StwDxFilterStartTime parameter defines the time in ms that the ‘no steering wheel activation’
confidence timer shall reach before the noise gate will floor any steering wheel input to 0. As long as the
confidence timer is below StwDxFilterStartTime, all steering wheel inputs will pass the noise gate.
Device
Index
Default
Value range
StwDxFilterThreshold
64020
2
0,1: Disable filtering
[2 ; 4095]: dPosition/dt
StwDxFilterStartTime
64021
0
0: filter always enabled
[0; 65515]: Time in ms
[65516 ; 65535]: Disables the timer
Example:
Analyzing the SASA data while the steering wheel is not activated, shows that the position change
fluctuates ± 2 peak-peak. Converted to steering wheel rpm, this corresponds to:
2 ticks • (1000 ms / 10 ms) • 60 sec / 4095 ticks = 2.9 rpm
Where:
•
•
•
10 ms is the steering wheel position change sampling period
(1000 ms / 10 ms) is the steering wheel position change per second
4095 is the position change measured in ticks for one steering wheel revolution.
To cut out any steering wheel activation below 2.9 rpm for more than 5 seconds, set
StwDxFilterThreshold equal to 2 and StwDxFilterStartTime equal to 5000. This will allow very slow
steering wheel activation below 2.9 rpm (or noise) for 5 seconds, before the noise gate cuts of the input.
The values in this example are suggested starting values for a tuning process.
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Steering by Steering Wheel – Open Loop
Steering by Steering Wheel – Open Loop
EHPS Type 2 System Diagram
Joystick or mini wheel
Steering angle sensor
OSP
OSP
Q
PVE EHPS
Valve
PVE
EHPS
valve
Q
Automatic steering
Steering
Steering
cylinder
cylinder
Position sensor
Vehicle speed
P005 225E
Acquire the Signals
See Mapping a Steering Device on page 34 on how to map the steering wheel sensor and steering wheel
angle sensor.
Functionality Tree
The tree below illustrates the functionality available in the PVED-CL for open-loop steering wheel
steering. The manufacturing default is found by following the red line. Following the instructions in this
chapter can of course modify it. The switches in the tree are used to select the functionality required. In
case different functionalities are required, the EHPS software provides multiple programs for each
steering device.
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switches
Sensitivity switch
Control principle switch
*
Cp
Ramp switch
Channel mapping switch
Steering by Steering Wheel – Open Loop
Sse
Program number: Y
Sr
Fixed
Sr=1
Var
Sr=2
No,
Sr=0
Fixed
Sse=1
Fixed
Sr=1
Var
Sr=2
No,
Sr=0
Related to
position of
steering actuator
Sse=2
Open loop
Cp=0
Related to
vehicle speed
Sse=3
Fixed
Sr=1
Var
Sr=2
No,
Sr=0
No signal (0)
Closed loop
Cp=255
CAN (255)
Fixed
Sse=1
Y=0
Open loop, fixed sensitivity, with fixed ramp times,
1
2
3
4
Open loop, fixed sensitivity, with variable ramp
times as function to vehicle speed,
Open loop, fixed sensitivity, with no ramps
applied.
Open loop, sensitivity related to steering actuator
position, with fixed ramp times
Open loop, sensitivity as function to steering actuator
position, with variable ramp times related to vehicle
speed,
Open loop, sensitivity related to steering actuator
position, no ramps applied
Open loop, sensitivity related to vehicle speed,
with fixed ramp times
Open loop, sensitivity related to vehicle speed,
with ramp times related to vehicle speed
Open loop, sensitivity related to vehicle speed,
no ramp times applied
Closed loop, fixed sensitivity
Related to
vehicle speed
Sse=3
Closed loop, sensitivity related to vehicle speed,
default
* Sensitivity means: number of revolutions on steering wheel from lock to lock
P005 202E
Open Loop Control
Open loop steering shall be chosen for implementing variable steering ratio or when sideward forces on
articulated steered vehicles must be actively reduced.
Block diagram oped loop steering wheel steering
Sse , Sts0, Sts1, Sts2,Sts3, Sts4, Sts5, Vesm, StrkVol, Vcap
100 ms
Ve
Steering
10 ms Vehicle speed
sensitivity
Yact
Actuator position
10 ms
X_stw
Steering
wheel
angle
Steering
10 ms
wheel
angle/dt
10 ms
Backlash
Transfer
function
Ri
Qm,Lx
Sr, Lr, Tro, Tfo, Lf,
Trh, Tfh, YsetFr, Tfr,
TAbortDownRamp,
Tra, Verm
Cf, Off
Yr, Yl
Ramp
function
Soft
stop
100 ms
Ve - Vehicle
speed
Q
Port flow
command
10 ms
Yact
Actuator
position
P005 206E
Select the Control Principle
Cp is used to select Open loop control for steering wheel steering by setting parameter index 1y02 equal
to 0. Parameter selection values: Y selects the program and ranges from 0 and 9.
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Steering by Steering Wheel – Open Loop
Apply Backlash
Ri If elasticity affects the sensor readings when the driver releases the steering wheel and hereby
unintentionally operates the valve, a backlash region (Ri) can be applied to prevent it. The size of the
backlash region is normally set equal to the angle related to elasticity.
However, any set-value greater than zero leads to slower steering responds. Therefore, to minimize these
effects, the steering wheel, sensor shaft and underlying mechanics as shown below must be designed as
stiff as possible.
Since this parameter only effects changes in the set point, stability problems in closed loop are not
related to the set-value of this parameter.
The default value does not remove elasticity effects.
Sensor
Steering wheel
Symbol
Index
Default
Value range
Ri
1y04
0 to 5
0 to 200
0 means 0 degrees backlash, 200 means ~17 degrees backlash. Backlash applies in both steering directions; therefore the total backlash region is twice
the threshold.
Set-point Transfer Function
The transfer function provides two parameters to transform steering wheel positional information to port
flow. It main function is to create the flow request set-point from the steering wheel sensor.
1000
Qr - requested port flow:
1 unit = 0.1% of Max port flow
CR - port
Example
Lx=10
Qm=-750
Max input signal
for activating the
steering device
CCW
-1000
-750
-500
Saturation
750
500
Qm
Lx
250
Sts
250
-250
500
-500
Saturation
750
1000
V - scaled steering
wheel speed: 1 unit
= 0.1% of Max
activation
-250
Defaults
Lx=0
Qm =1000
Max input signal
for activating the
steering device
CW
-750
-1000
CL - port
P005 203E
Lx affects the inherent linearity between steering actuator speed and steering wheel speed. The set value
affects the linearity of a second order function. Increase Lx to achieve slower cylinder speed at low
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Open Loop
steering wheel RPMs and consequently higher cylinder speeds at higher steering wheel RPMs. The
default value gives a linear relationship between steering wheel RPM and cylinder speed.
Qm sets the maximum port flow. It defines the maximum achievable cylinder speed for steering left and
right. The default value is set to maximum flow and thus dependent on the maximum flow of the applied
valve.
Symbol
Index
Default
Value range
Lx
1y06
0
-10 max regressive, 0 (linear) to 10 (max progressive)
Qm
1y27
1000
0 to 1000 (100% flow at CL or CR port)
Steering Sensitivity
Sensitivity is set individually for each program and can be either fixed or variable. Sensitivity can depend
on vehicle speed, steered wheel position, or change of current device program. Using variable sensitivity
can increase comfort and controllability significantly, and depending on the vehicle type and use, the
appropriate way to achieve the change might be different. The PVED-CL allows 10 different programs for
the steering wheel steering with different sensitivity settings. Each program can be applied via the MMI
while driving. Each program can then use either fixed or variable sensitivity – hence we talk ‘secondorder-variability’ by using the PVED-CL.
Max Sts = 1200
Vesm = 500
Vehicle speed dependant
(linear) – program 1
420
Vehicle speed dependant
(non-linear) – program 2
400
Fixed sensitivity – program 0
380
Vehicle speed dependant
(non-linear) – program 3
360
Sts5
Sts4
Sts3
Sts0
Sts1
Sts2
340
Min Sts = 20
0
100
200
300
400
500
600
700
Ve = Vehicle speed: 1 unit = 0.1 km/h
800
900
1000
Vehicle speed
A note on variable steering ratio:
In systems with an EHPS valve, the sensitivity settings yield equivalent steering ratio results on the
physical steering system.
In systems with an EH valve, the software does not take the parallel flow contribution from the OSP into
account. Unless compensated for, the resulting steering ratio on the physical steering system will be
lower than expected. To compensate, increase the sensitivity parameters and optionally limit the
maximum flow (Qm) to achieve the desired steering ratio for the used steering programs.
Select a Fixed Sensitivity
Vcap holds information about the actual valve capacity. This information is needed by the software to
achieve the desired sensitivity.
StrkVol holds information about the actual stroke volume (cylinder size). This information is needed by
the software to achieve the desired sensitivity.
Sse selects between a fixed steering sensitivity, variable to steering actuator position or vehicle speed.
Set Sse to 1 to select the fixed sensitivity
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PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Open Loop
Sts0 defines the fixed steering ratio. This value shall be set large enough to provide sufficient directional
stability at all vehicle speeds. The default value is set to a commonly applied steering ratio.
Symbol
Index
Default
Value range
Vcap
706
25
5 to 120 (l/min)
StrkVol
707
600
100 to 8000 (cm3)
Sse
1y09
1
Must be set at 1
Sts0
1y10
400
20 to 1200
A steering ratio of 400 equals to 4.00 steering wheel turns to move the steering actuator from YL to YR (left to right end-lock position)
Select a Sensitivity with Relation to Actuator Position
A variable steering sensitivity related to actuator position is normally chosen for increased controllability
for straightforward driving (for e.g. material handling applications). The correlation between steering
wheel movements and the cylinder position is normally closely related to the mechanical geometry
between steering actuator and steered wheels of the individual vehicle.
Sts(Yact) saturates
420
Sts0=400
400
Sts1=400
380
End lock position
Steering sensitivity Sts
(Yact)
max Sts = 1200
360
340
min Sts = 20
Straight forward driving position
0
100
200
300
400
500
600
700
800
900 1000
Yact - Steering actuator position: 1 unit = 0.1% of max position
P005 091E
The correlation is defined by two parameters. The steering sensitivity between two table coordinates is
found by linear interpolation. The functionality is symmetrical around neutral.
Vcap holds information about the actual valve capacity. This information is needed by the software to
achieve the desired sensitivity.
StrkVol holds information about the actual stroke volume (cylinder size). This information is needed by
the software to achieve the desired sensitivity.
Sse selects between a fixed steering sensitivity, variable to steering actuator position or vehicle speed.
Set Sse to 2 to select the sensitivity related to steering actuator position.
Sts0 sets the linear gradient between steering angle and requested port flow for steering straight
forward. When the steering actuator signal unintentionally is not mapped, Sts(Yact) will be equal to Sts0,
since variable Yact remains 0.
Sts1 sets the linear gradient between steering angle and requested port flow for steering at with the
minimum turning radius.
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PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Open Loop
Symbol
Index
Default
Value range
Vcap
706
25
5 to 120 (L/min)
StrkVol
707
600
100 to 8000 (ccm)
Sse
1y09
1
Must be set at 2
Sts0
1y10
400
20 to 1200
Sts1
1y11
See Mapping a Steering Device on page 34.
Steering actuator Sensor (feedback from vehicle wheels)
Steering actuator position to acquire “steering actuator position”.
Select a Sensitivity with Relation to Vehicle speed
Variable steering sensitivity related to vehicle speed is normally used to optimize steering controllability
at higher driving speeds. The parameter values and correlation is normal closely related to the present
vehicle dynamics of the individual vehicle model.
The correlation is defined by seven parameters. All Sts-parameters may be set equal to each other or
monotonically increasing for higher vehicle speeds. The steering sensitivity between two table
coordinates is found by linear interpolation. The relation is equal for negative speeds.
max Sts = 1200
Vesm=500
Sts (Ve) saturates
example
Sts1=400
Sts5=400
Sts4=400
360
Sts3=400
380
Sts2=400
400
Sts0=400
Steering sensitivity Sts (Ve)
420
340
min Sts = 20
0
100
200
300
400
500
600
700
800
Ve = Vehicle speed: 1 unit = 0.1 km/h
900 1000
P005 204E
Vcap holds information about the actual valve capacity. This information is needed by the software to
achieve the desired sensitivity.
StrkVol holds information about the actual stroke volume (cylinder size). This information is needed by
the software to achieve the desired sensitivity.
Sse selects between a fixed steering sensitivity, variable to steering actuator position or vehicle speed.
Set Sse to 3 to select the sensitivity related to vehicle speed.
Sts0 sets the steering ratio when the vehicle is standing still. Sts0 applies at all times when the vehicle
signal unintentionally is not configured as PRESENT (Ve remains 0). In case the vehicle speed signal is not
diagnosed, it is recommended to set Sts0 at a value where sufficient directional stability at maximum
vehicle speed is present. The default value is set to a value which yelds good controllability at high
vehicle speeds.
Sts1 sets the steering ratio when the vehicle is driving at 6.25% of Vesm.
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PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Open Loop
Sts2 sets the steering ratio when the vehicle is driving at 12.50% of Vesm.
Sts3 sets the steering ratio when the vehicle is driving at 25.00% of Vesm.
Sts4 sets the steering ratio when the vehicle is driving at 50.00% of Vesm.
Sts5 sets the steering ratio when the vehicle is driving at 100.00% of Vesm.
Vesm sets the region where steering sensitivity is variable to vehicle speed. The default value is set at the
maximum speed of most applications.
Symbol
Index
Default
Value range
Vcap
706
25
5 to 120 (L/min)
StrkVol
707
600
100 to 8000 (ccm)
Sse
1y09
1
Must be set at 3
Sts0
1y10
400
20 to 1200
Sts1
1y11
400
Sts0 to 1200
Sts2
1y12
400
Sts1 to 1200
Sts3
1y13
400
Sts2 to 1200
Sts4
1y14
400
Sts3 to 1200
Sts5
1y15
400
Sts4 to 1200
Vesm
1y16
500
1 to 1000 (0.0 to 100.0 km/h)
Please note the parameter dependency of Sts. Steering sensitivity of 400 equals to 4.00 steering wheel turns to move the steering actuator from YL to
YR (left to right end-lock position) See chapters Mapping a Steering Device on page 34 and J1939 Diagnostic Interface on page 115 to acquire vehicle
speed.
Ramps (Anti-jerk)
Ramps are normally used to minimize jerk forces in machines with articulated steered steering systems. In
these steering systems, the articulating masses can be instantly stopped by closing the valve oil flow. An
instant cylinder movement stop starts the articulating masses to oscillate until all kinetic energy is
dispatched into heat by the shock valves or by the friction between wheels and ground. Jerk is an
inherent characteristic of articulated steered vehicles and cannot be completely removed. However, it is
best minimized when the forces are monotonically reduced in magnitude.
To achieve this, the EHPS software provides linear or non-linear ramps which in effect creates an orifice
across the main spool to tank by holding the valve open near its closing position until all kinetic energy is
dispatched into heat for some time. Ramps work on the valve spool set-point.
Ramps with Fixed Ramp Times
Sr sets the method. The ramp times can be disabled, fixed or related to vehicle speed. Set Sr to:
•
•
•
0 to select no ramps (default),
1 to select fixed ramp times, or
2 for speed dependent ramp times.
Symbol
Index
Default
Value range
Sr
1y17
0
0 (default)
The figure below shows the operation of ramps with fixed ramp times and illustrates different ramp
scenarios. Qr is the request port flow commanded with the steering wheel. Qramp the ramp limited port
flow and can be regarded as the result of the ramp function.
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Open Loop
Qr, Qramp
Qr Requested port flow
Qramp ramp port flow
YsetFr
YAbortDownRamp
1 unit = 0.1% of max. port flow
1000
YsetFr, fast ramp down range
750
500
slow ramp down range
250
YAbortDownRamp
0
-250
-500
-750
Tfr
Tro
Tfo
Up ramp
Slow down ramp
}
Abort down ramp
time
}
Slow down ramp
-YsetFr
-1000
}
Fast down ramp
P005 205E
Sr Selects the ramp type. The ramp function can be disabled, fixed or related to vehicle speed. Set Sr to 1
to select fixed ramps.
Lr Sets the linearity of the ramp-up curve. The default value is a linear ramp.
Lf Sets the linearity of the slow ramp-down curve. The default value is a linear ramp.
Tro Sets the ramp-up time to open the valve from zero to max port flow. The time applies for both ports.
To gain the best performance, the ramp-up time shall be set larger than the inherent ramp up time of the
main spool. See Technical Data on page 24 for these ramp times.
Tfo Sets the ramp-down time to close the valve from max to zero port flow. The time applies for both
ports. It has most effect when the ramp-up time is set larger than the inherent ramp down time of the
main spool. See Technical Data on page 24 for these ramp times.
YsetFr Experience shows that ramping down from maximum flow towards medium flows do not cause
as much jerk as ramping down from medium flows towards no flow (close to the valve dead-bands). In
order to “expedite” the ramping at large flows, a flow range can be set up where the spool can move
faster down to a flow range, where the slow down ramp is active. The overall goal with the parameter is
too optimize steering response time without degrading the anti-jerk performance. Set up fast ramp down
time Tfr before tuning this parameter. Setting YsetFr to 1000 eliminates the effect of the fast ramp down.
Typical settings are 500-800. Use trial and error.
Example:
A value of 800 can be interpreted as allowing the spool to ramp down with a fast ramp for flow requests
between maximum flow (1000) and 800/1000 of maximum flow.
Tfr This time defines the applied ramp time in the fast ramp-down range. It is defined as the ramp time
from maximum flow to no flow. This means that in practice, the actual fast ramp-down time is
proportional to the fast ramp-down range divided by 1000.
Use this optimization criterion: Ramp down as fast as possible for flow ranges, where jerks are not
significant. Typical values are 1-50 ms. The fast ramp down time shall always be less than the slow rampdown time. Once the value is set, it should not be adjusted anymore during further ramp parameter
optimization.
YAbortDownRamp To come around the problem of slow steering response for large down-ramp times,
especially if a sudden emergency change of direction is needed, a slow down-ramp can be aborted by
requesting a flow in the opposite direction. Once a slow down-ramp is aborted, an abort down-ramp
time, Tra is applied. Obviously Tra shall be significantly smaller than the slow down-ramp to get any
effect.
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Open Loop
Tra is the ramp-down time applied when the slow down-ramp is aborted. This rampdown time shall
typically be much lower than the slow ramp-down time, Tfo, in order to gain any increased steering
responsiveness. Typical value is half the value of Tfo or Tfh time if vehicle speed dependency is applied
(Sr=2). Use trail and error.
Example:
A value equal to 500 means that the driver needs to steer out 500/1000 of maximum flow before the slow
down-ramp is aborted. 500 again corresponds to a certain steering wheel RPM.
Typical values are 100-300 to have the abort down ramp possibility and to avoid unintentional abort of
the down ramp due to steering wheel activation due to vibrations. Setting the value to 1000 disables the
abort down ramp functionality.
Symbol
Index
Default
Value range
Sr
1y17
0
Must be set at 1
Lr
1y19
0
0 (linear) to 10 (max progressive)
Lf
1y20
0
0 to 10
Tro
1y21
1
1 to 1000 (ms)
Tfo
1y23
350
1 to 1000 (ms)
YsetFr
1y32
1000
0 to 1000 (1 unit = 0.1% of max. flow)
Tfr
1y33
100
1 to 1000 ms
Tfr shall be smaller than Tfo and less than 150 ms.
YAbortDownRamp
1y34
0
0 to 500 (1 unit = 0.1% of max. flow).
The default value will force an down-ramp abort at a slight reverse port flow request.
Typically YAbortDownRamp needs be increased to avoid unintentional down-ramp
aborts as this will infer a jerk on the driver.
Tra
1y35
1
1 to 1000 ms
Ramp-down time for canceled down-ramp
The discontinuities in the progressive characteristic are located at 50, 120 and 333 ([5.0;T at 25], [12,0;T at 50] and [33.3;T at 75] of max port flow
capacity)
Select Ramps with Ramp Times Related to Vehicle Speed
Often, slow ramps are not convenient at high speeds and results in difficulties driving precise and
straight. Including the vehicle speed information will allow the software to interpolate between
maximum and minimum ramp times as a function of vehicle speed.
Ramp time T(Ve) is determined by interpolating between Tro and Tfo as well as Tfo and Tfh as shown in
the figure below. The relation is equal for negative speeds.
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Open Loop
500
400
300
200
Default:
Verm=500
Tro=1
Trh=1
100
Tro
min time = 1
0
100
200
300
Verm
T (Ve) - Ramp up time in ms
max time = 1000
T(Ve) saturates
Trh
400
500
600
700
800
900 1000
Ve - Vehicle speed: 1 unit = 0.1 km/h
500
Default:
Verm=500
Tfo=350
Tfh=200
400
Tfo
300
T (Ve) saturates
Tfh
200
Verm
T(Ve) -
Ramp down time in ms
max time = 1000
100
min time = 1
0
100
200
300
400
500
600
700
800
900 1000
Ve - Vehicle speed: 1 unit = 0.1 km/h
P005 220E
Sr Selects the ramp type. The ramp function can be disabled, fixed or related to vehicle speed. Set Sr to 1
to select fixed ramps.
Lr Sets the linearity of the ramp-up curve. The default value is a linear ramp.
Lf Sets the linearity of the slow ramp-down curve. The default value is a linear ramp.
Tro Sets the ramp-up time to open the valve from zero to max port flow when the vehicle speed is 0
kmph. The time applies for both ports. To gain the best performance, the ramp-up time shall be set larger
than the inherent ramp up time of the main spool.
See Technical Data on page 24 for these ramp times.
Tfo Sets the ramp-down time to close the valve from max to zero port flow when the vehicle speed is 0
kmph. The time applies for both ports. It has most effect when the ramp-up time is set larger than the
inherent ramp down time of the main spool.
See Technical Data on page 24 for these ramp times.
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Open Loop
Trh Sets the ramp-up time to open the valve from zero to max port flow when the vehicle speed is equal
to Verm kmph. The time applies for both ports. To gain the best performance, the ramp-up time shall be
set larger than the inherent ramp up time of the main spool.
See Technical Data on page 24 for these ramp times.
Tfh Sets the ramp-down time to close the valve from max to zero port flow when the vehicle speed is
equal to Verm kmph. The time applies for both ports. It has most effect when the ramp-up time is set
larger than the inherent ramp down time of the main spool.
See Technical Data on page 24 for these ramp times.
Verm Sets the region (in kmph) where ramp-up (Trh) and ramp-down (Tfh) time is variable to vehicle
speed.
YsetFr Experience shows that ramping down from maximum flow towards medium flows do not cause
as much jerk as ramping down from medium flows towards no flow (close to the valve dead-bands). In
order to “expedite” the ramping at large flows, a flow range can be set up where the spool can move
faster down to a flow range, where the slow down ramp is active.
The overall goal with the parameter is too optimize steering response time without degrading the antijerk performance. Set up fast ramp down time Tfr before tuning this parameter. Setting YsetFr to 1000
eliminates the effect of the fast ramp down.
Typical settings are 500-800. Use trial and error.
Example:
A value of 800 can be interpreted as allowing the spool to ramp down with a fast ramp for flow requests
between maximum flow (1000) and 800/1000 of maximum flow.
Tfr This time defines the applied ramp time in the fast ramp-down range. It is defined as the ramp time
from maximum flow to no flow. This means that in practice, the actual fast ramp-down time is
proportional to the fast ramp-down range divided by 1000.
Use this optimization criterion: Ramp down as fast as possible for flow ranges, where jerks are not
significant. Typical values are 1-50 ms. The fast ramp down time shall always be less than the slow rampdown time. Once the value is set, it should not be adjusted anymore during further ramp parameter
optimization.
YAbortDownRamp To come around the problem of slow steering response for large down-ramp times,
especially if a sudden emergency change of direction is needed, a slow down-ramp can be aborted by
requesting a flow in the opposite direction. Once a slow down-ramp is aborted, an abort down-ramp
time, Tra is applied. Obviously Tra shall be significantly smaller than the slow down-ramp to get any
effect.
Example:
A value equal to 500 means that the driver needs to steer out 500/1000 of maximum flow before the slow
down-ramp is aborted. 500 again corresponds to a certain steering wheel RPM.
Typical values are 100-300 to have the abort down ramp possibility and to avoid unintentional abort of
the down ramp due to steering wheel activation due to vibrations. Setting the value to 1000 disables the
abort down ramp functionality.
Symbol
Index
Default
Value range
Sr
1y17
0
must be set to 1
Lr
1y19
0
0 (linear ) to 10 (max progressive)
Lf
1y20
0
Tro
1y21
1
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1 to 1000 ms
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Open Loop
Symbol
Index
Default
Value range
Tfo
1y23
350
Trh
1y22
1
Tfh
1y24
350
Verm
1y25
500
1 to 1000 (1 unit is 0.1 km/h)
YsetFr
1y32
1000
0 to 1000 (1 unit = 0.1% of max. flow)
Fast ramp-down is active in the port flow request range 1000 to YsetFr. The default
value disables fast ramp-down.
Tfr
1y33
100
1 to 1000 ms.
Tfr shall be smaller than Tfo and less than 150 ms.
YAbortDownRamp
1y34
0
0 to 500 (1 unit = 0.1% of max. flow).
The default value will force an down-ramp abort at a slight reverse port flow
request. Typically YAbortDownRamp needs be increased to avoid unintentional
down-ramp aborts as this will infer a jerk on the driver.
The discontinuities in the progressive characteristic are located at 50, 120 and 333.
([5.0;T at 25], [12,0;T at 50] and [33.3;T at 75] of max port flow capacity)
Anti-jerk Ramp Parameter Tuning Guide
Tuning the parameters is an iterative process. The following sequence may be useful when tuning a
vehicle:
1. Initial setting: Set Tro to Set Tfr to Set YsetFr to 1000. Set Tra to 1. Set YabortThreshold to 500.
2. Set the ramp-down time , Tfo, to a start value e.g. 500.
3. Decrease YsetFr from 1000 towards a smaller number. Observe which value of YsetFr where the level
of jerks starts to get worse to find the flow request range, where ramping has an effect. Optionally
increase Tfr to optimize on the fast ramp-down operation. Tfr should not exceed 150 ms and always
be smaller than Tfo.
4. Adjust the ramp-down time, Tfo, until at good anti-jerk performance is achieved.
5. Increase the ramp-up time, Tro, to further improve the anti-jerk performance. Tro is typically smaller
than Tfo.
6. Fine-tune the performance by experimenting with Tfr, Tra, and YsetFr. Note that the largest jerks shall
be tuned away with the ramp-up time, Tro, and ramp-down time, Tfo.
7. Finally the YAbortThrehold and Tra may be adjusted. Consider how many steering wheel RPM is
needed to abort the down-ramp. Secondly, adjust Tra to reduce the jerk when aborting the downramp. Obviously, Tra needs to be less than the down-ramp time, Tfo to get a faster steering response.
Typical values for Tra is 50 – 100 ms.
The above typical parameter settings may vary from vehicle to vehicle.
Soft (Cushion) End-stop
To prevent the steering actuator to hit the mechanical end lock with great speed, the PVED is able to slow
down the actuator speed when approaching the end lock electronically. The red line in the figure below
shows how the actuator is slowed down near the end lock position. The black line in the figure below
shows how port flow is reduced. The steering actuator signal must be present in the PVED for this
functionality to work.
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Open Loop
Right end lock
1000
Cf
Yr, Software end lock position
500
Port flow
command
Steering actuator position
250
time
0
Off
Yact - steering actuator position
Q - port flow command
750
-250
Defaults
250 ms
Yl=-1000
-500
Yr=1000
-750
Cf=350
Off=50
-1000
Yl, Software end lock position
Left end lock
P005 221E
Yr, Yl The difference between the values of both parameter set the freedom of the steering actuator.
Normally, Yr is set equal at the right mechanical end lock. Yl is normally set equal to the left mechanical
end lock. For example, setting Yr at 500 and Yl at –500 reduces the freedom of the actuator by 50%.
The default values for Yr and Yl are set equal to position of the mechanically end locks.
Cf Sets the region where actuation speed is slowed down. This region starts from the position defined by
Yr and Yl. Making this region to small reduces or can eliminate the effect of soft stop. The default value for
Cf ensures the valve is closed proportionally with actuator position.
In order to slow down in a controlled manner, the inherent shortest time for the PVED to move the spool
from max open to be fully closed has to be considered. This ramp down time can be found in Technical
Data on page 24.
Off This parameter sets the permitted actuation speed when hitting the end lock defined by Yr or Yl.
When the steering actuator passed Yr or Yl, actuation speed will decay to zero.
The default sets a speed that allows building up pressure when the actuator is located at Yr or Yl.
Symbol
Index
Default
Value range
Yr
10y7
1000
-1000 – 1000, Values smaller than 0 will be set equal to the positive equivalent
Yl
10y8
-1000
-1000 – 1000, Values greater than 0 will be set equal to the negative equivalent
Off
1y28
50
0 to 1000 (0.0 - 100.0% of max port flow)
Cf
1y29
333
1 to 1000
See chapters Mapping Steering Signals, Steering Actuator Sensor (feedback from vehicle wheels) and Steering Actuator Position to acquire “steering
actuator position”.
Main Spool Dead-band Control Function
Tolsout maximum time where the main spool is allowed to be operated proportionally within the valve
dead-bands. The main spool control range for this function can be seen on the Dead-band Jump Control
on page 55. This function is useful to eliminate frequent spool relocating events from its neutral to its
dead-band position and back (so called jumps) at low steering wheel speeds.
The flow request is 0 while moving the steering wheel within the defined steering wheel backlash range
(see Apply Backlash on page 44).
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Operation Manual
Steering by Steering Wheel – Open Loop
Dead-band Jump Control
Set Tolsout lower than 21 (ms) to momentarily set the main spool in neutral as soon as the flow request is
0, No proportional main spool movement will take place. The spool will jump from neutral to either of the
valve dead-bands depending on the flow request. The backlash parameter has no impact for these
Tolsout values.
Dead-band Hold and Proportional Control
Setting Tolsout between 21 and 30 000 (ms) defines the maximum time where the main spool is either
set on the valve dead-band or controlled proportionally within the dead-band (granted that the flow
request is 0 during this time).
After a flow request to either left or right port, the main spool will be set on the respective left or right
valve dead-band. Any steering wheel movement within the defined backlash region will result in
proportional main spool movement as a function of the steering wheel movement. Proportional control
will be allowed for Tolsout ms.
If the flow request has been 0 for Tolsout ms, the main spool will be set in neutral and any steering wheel
movements within the backlash range is ignored.
To utilize proportional control, a steering wheel backlash range needs to be created. If the backlash range
is set a low value, the main spool will effectively be operated as dead-band jump control.
Responding to Flow Requests after Tolsout
If the main spool has been set in neutral after Tolsout ms, any flow request will cause the spool to
immediately jump to the relevant spool position with no initial proportional dead-band control.
Symbol
Index
Default
Value range
Tolsout
116
10 000
1 to 30 000 (ms)
Magnetic Valve Control
Magnetic valves off delay time disables the magnetic valve bridge after a time specified in ms when the
flow request is 0, otherwise it remains enabled. This parameter is used when electrical energy
consumption by the solenoid bridge in the PVED must be reduced or to remove a steering control
conflict between the OSP and the PVED.
The default value disables this functionality i.e. the magnetic valve bridge is enabled at all times.
Generally, the magnetic valve bridge is enabled when the PVED-CL receives a non-zero flow request.
Symbol
Index
Default
Value range
Magnetic valves off delay time
115
30 000
1 to 30 000 (ms)
If Qm is set to 0, then the magnetic valve bridge will be disabled immediately when the SASA sensor is
the selected device.
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Closed Loop
Steering by Steering wheel – Closed Loop
Closed loop steering by wheel steering is chosen when:
•
•
•
•
The knob of the steering wheel must return in the same position for straight forward driving
Accurate steering sensitivity is required
Steering motion is required at extreme low steering wheel speeds
Hold the steering actuator at a fixed position when steering wheel speed is zero.
W
Warning
Steering by steering wheel in closed loop mode shall only applied in systems with a PVED-CL and an
EHPS valve. Using an OSP and an EH valve in closed-loop is not a valid configuration and will lead to
unpredictable closed loop performance.
Functionality Tree
switches
Sensitivity switch
Control principle switch
*
Cp
Ramp switch
Channel mapping switch
The tree below illustrates the functionality available in the PVED-CL for closed-loop steering wheel
steering. The manufacturing default is found by following the red line. Following the instructions in this
chapter can of course modify it. The switches in the tree are used to select the functionality required. In
case different functionalities are required, the EHPS software provides multiple programs for each
steering device.
Sse
Sr
Fixed
Sse=1
Related to
position of
steering actuator
Sse=2
Open loop
Cp=0
Related to
vehicle speed
Sse=3
Program number: Y
Fixed
Sr=1
Var
Sr=2
No,
Sr=0
Fixed
Sr=1
Var
Sr=2
No,
Sr=0
Fixed
Sr=1
Var
Sr=2
No,
Sr=0
No signal (0)
Closed loop
Cp=255
CAN (255)
Fixed
Sse=1
Related to
vehicle speed
Sse=3
Y=0
Open loop, fixed sensisitivity, with fixed ramp times,
1
2
3
4
Open loop, fixed sensisitivity, with variable ramp
times as function to vehicle speed,
Open loop, fixed sensisitivity, with´no ramps
applied.
Open loop, sensisitivity related to steering actuator
position, with fixed ramp times
Open loop, sensisitivity as function to steering actuator
position, with variable ramp times related to vehicle
speed,
Open loop, sensisitivity related to steering actuator
position, no ramps applied
Open loop, sensisitivity related to vehicle speed,
with fixed ramp times
Open loop, sensisitivity related to vehicle speed,
with ramp times related to vehicle speed
Open loop, sensisitivity related to vehicle speed,
no ramp times applied
Closed loop, fixed sensisitivity
Closed loop, sensisitivity related to vehicle speed,
default
* Sensitivity means: number of revolutions on steering wheel from lock to lock
For safety reasons, an anti wind up function prevents the steering actuator to lag behind the drivers
steering intends. The function is typically needed when not enough flow is supplied to the steering
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PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Steering Wheel – Closed Loop
system at high steering wheel speeds combined with a low steering ratio or when not enough pressure is
provided when the driver steers against a high resistance. Under these conditions and without effective
measures it might significantly reduce the ability to steer the vehicle at higher speeds. The anti wind up
function operates continuously and will limit the set point when commanded port flow exceeds the max
flow capacity of the valve. These events always increase the number of steering wheel turn from lock to
lock.
Block diagram closed loop steering wheel steering
Sse,
Sts0,Sts1,Sts2,Sts3,
Sts4,Sts5, Vesm
100 ms
Vehicle
speed
10 ms Steering
wheel
angle
10delta
ms
angle
Kd,Kc
Steering
sensitivity
Anti drift
Backlash
Anti
windup
Feedforward
Yr,Yl,Lx
Transfer
function
Port flow
limiter
Kp
actuator
position
Ri
Qm
Port flow
command
10 ms
Select the Control Principle
Cp selects the closed loop control for steering wheel steering. Parameter index 1y02 must be set equal to
255. Parameter selection values: Y selects the program and ranges from 0 and 9.A fixed value of Y must
be consistently used throughout the entire configuration of a single program.
Acquire the Signals
See Mapping a Steering Device on page 34 on how to map the steering wheel sensor and steering wheel
angle sensor.
Apply Backlash
Ri If elasticity affects the sensor readings when the driver releases the steering wheel and hereby
unintentionally operates the valve, a backlash region (Ri) can be applied to prevent it. The size of the
backlash region is normally set equal to the angle related to elasticity.
However, any set-value greater than zero leads to slower steering responds. Therefore, to minimize these
effects, the steering wheel, sensor shaft and underlying mechanics as shown below must be designed as
stiff as possible.
Sensor
Steering wheel
Since this parameter only effects changes in the set point, stability problems in closed loop are not
related to the set-value of this parameter.
The default value does not remove elasticity effects.
Symbol
Index
Default
Value range
Ri
1y04
0
0 to 200
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Steering by Steering Wheel – Closed Loop
Symbol
Index
Default
Value range
0 means 0 degrees backlash, 200 means ~17 degrees backlash. Backlash applies in both steering directions; therefore the total backlash region is twice
the threshold.
Steering Sensitivity
Sensitivity is set individually for each program and can be either fixed or variable. Variability can depend
on vehicle speed or change of current device program.
Using variable sensitivity can increase comfort and drivability significantly, and depending on the vehicle
type and use the appropriate way to achieve the change might be different.
The PVED-CL allows several programs for each steering device, which means that 5 to 10 different
programs with different sensitivity settings can be made and applied via the MMI while driving. Each
program can then use either fixed or variable sensitivity – hence we talk ‘second-order-variability’ by
using the PVED-CL.
Max Sts = 1200
Vesm = 500
Vehicle speed dependant
(linear) – program 1
420
Vehicle speed dependant
(non-linear) – program 2
400
Fixed sensitivity – program 0
380
Vehicle speed dependant
(non-linear) – program 3
360
Sts5
Sts4
Sts3
Sts0
Sts1
Sts2
340
Min Sts = 20
0
100
200
300
400
500
600
700
Ve = Vehicle speed: 1 unit = 0.1 km/h
800
900
1000
Vehicle speed
Select a Fixed Steering Sensitivity
Sse selects between a fixed steering sensitivity, variable to steering actuator position or vehicle speed.
Set Sse to 1 to select the fixed sensitivity.
Sts0 set the steering ratio. This value should provide sufficient directional stability at all vehicle speeds.
The default value is set at a steering ratio most used.
Symbol
Index
Default
Value range
Sse
1y09
1
Must be set at 1
Sts0
1y10
400
20 to1200
A steering ratio of 400 equals to 4.00 steering wheel turns to move the steering actuator from YL to YR (left to right end-lock position)
Select a Sensitivity with Relation to Vehicle Speed
Variable steering sensitivity related to vehicle speed is normally used to optimize steering controllability
at higher driving speeds. The values & correlation is normal closely related to the present vehicle
dynamics of the individual vehicle model.
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Steering by Steering Wheel – Closed Loop
The correlation is defined by seven parameters. All Sts-parameters may be set equal to each other or
monotonically rising for higher vehicle speeds. The steering sensitivity between two table coordinates is
found by linear interpolation. The relation is equal for negative speeds.
max Sts = 1200
Vesm=500
Sts (Ve) saturates
example
Sts1=400
Sts5=400
Sts4=400
360
Sts3=400
380
Sts2=400
400
Sts0=400
Steering sensitivity Sts (Ve)
420
340
min Sts = 20
0
100
200
300
400
500
600
700
800
Ve = Vehicle speed: 1 unit = 0.1 km/h
900 1000
P005 204E
Variable steering sensitivity related to actuator position, is normally applied to have a higher sensitivity
around neutral (driving straight) and lower sensitivity at different turning angles.
Sse selects between a fixed steering sensitivity, variable to steering actuator position or vehicle speed.
Set Sse to 3 to select the sensitivity related to vehicle speed.
Sts0 sets the steering ratio when the vehicle is standing still. Sts0 applies at all times when the vehicle
signal unintentionally is not configured as PRESENT (Ve remains 0). In case the vehicle speed signal is not
diagnosed, it is recommended to set Sts0 at a value where sufficient directional stability at maximum
vehicle speed is present. The default value is set a value common to fast driving mobiles
Sts1 sets the steering ratio when the vehicle is driving at 6.25% of Vesm.
Sts2 sets the steering ratio when the vehicle is driving at 12.50% of Vesm.
Sts3 sets the steering ratio when the vehicle is driving at 25.00% of Vesm.
Sts4 sets the steering ratio when the vehicle is driving at 50.00% of Vesm.
Sts5 sets the steering ratio when the vehicle is driving at 100.00% of Vesm.
Vesm sets the region where steering sensitivity is variable to vehicle speed.
The default value is set at the maximum speed of most applications.
Symbol
Index
Default
Value range
Sse
1y09
1
Must be set at 3
Sts0
1y10
400
20 to 1200
Sts1
1y11
400
Sts0 to 1200
Sts2
1y12
400
Sts1 to 1200
Sts3
1y13
400
Sts2 to 1200
Sts4
1y14
400
Sts3 to 1200
Sts5
1y15
400
Sts4 to 1200
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Steering by Steering Wheel – Closed Loop
Symbol
Index
Default
Value range
Vesm
1y16
500
1 to 1000 (0.0 to 100.0 km/h)
Please note the parameter dependency of Sts. Steering sensitivity of 400 equals to 4.00 steering wheel turns to move the steering actuator from YL to
YR (left to right end-lock position) See chapters Mapping steering signals and J1939 Vehicle Speed to acquire vehicle speed.
Create the Set-point
The transfer function provides three parameters to relate a sum of scaled steering wheel angle
increments to steering actuator set point position. The scaled steering wheel position is a sum of steering
wheel angle increments corrected by the current applied steering sensitivity and scaled according to the
operating ranges of variable Yact.
Right steering
Steering actuator
position setpoint
Example
Lx = 10
YR = -750
YL = 500
YL
500
250
-1000
-750
-500
250
-250
-250
-500
Defaults
Lx = 0
YR = 1000
YL = -1000
-750
saturation
YR
Lx
Sum of scaled delta steering
wheel angle increments
1 unit = 0.1% of
steering actuator at the
left end lock position
Min sum for
activating the
steering wheel
CCW
750
Saturation
1 unit = 0.1% of
steering actuator at the
right end lock position
1000
actuator end-lock
-1000
500
750
1000
Max sum for
activating the
steering wheel
CW
1 unit=Sts/2000 % of 1
steering wheel revolution
Left steering
actuator end- lock
P005 201E
Lx Sets the curve linearity. The parameter is set down when the cylinder position is too far (over-steer) for
small steering angles or vice versa. The optimum value for this parameter is closely related to the
inherent linearity between steering actuator position and signal. This inherent linearity depends very
much whether a linear sensor is used to detect cylinder piston position or an angular sensor at the king
pin. Lx is typical set at zero when the cylinder piston position is detected using a linear sensor. When the
king pin rotation is detected with an angular sensor at the king pin, Lx is typical set between 2 and 4.
The default value will not effect the resulting relation.
YR, YL The difference between the set values of both parameters define the freedom of the steering
actuator. Normally, YR is set equal at the mechanical end lock that steers the vehicle into a right direction.
YL is normally set equal to the mechanical end lock that steers the vehicle into a left direction. In case an
opposite steering behavior is required, YR must be set at the negative equivalent. YL must be set at the
positive equivalent.
The default value for YR and YL is set equal to the mechanical locks of the steering actuator and provides
steering in the right direction.
Symbol
Index
Default
Value range
Lx
1y06
0
-10 to 10
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Operation Manual
Steering by Steering Wheel – Closed Loop
Symbol
Index
Default
Value range
YR
1y07
1000
-1000 to 1000; Yr ≠ 0
YL
1y08
-1000
-1000 to 1000; YI ≠ 0
Lx in quadrant 1 or 4 is located at: [500;Yr*(20-Lx)/40], Lx in quadrant 2 or 3 is located at: [-500;Yl*(20-Lx)/40]
YR and YL may not both be zero nor have same sign.
Closing the Loop
Feed-forward
This variable is used to feed the drivers steering intends forward to the valve. It minimizes effectively lag
in the steering actuator motion. The feed forward has most effect when the system responds 80 to 90%
of the exact intend. This is accomplished by scaling steering wheel speed using the following parameter:
StrkVol scales the feed forward in order to get the specified number of steering wheel turns within the
end-locks. It represents the stroke volume between the mechanical end-locks in cm3.
Kp must be temporarily set at zero to eliminate the closed loop contribution while tuning. Tuning is
finished when the number of steering wheel turns from lock to lock is at 80 to 90 % of the turns specified.
If 4 turns was specified, the number of turns should be between 4.4 and 4.8.
Steady State Error
Since the steering actuator acts as a free integral and the dead band in the valve is compensated in
software, the loop does not necessarily include a second integrate term to achieve accuracy. The
controller in EHPS software has therefore only a proportional term, which keeps tuning relatively simple.
To achieve steady state accuracy:
•
•
•
The difference between the location of spool dead band specified in the spool compensation
function in the EHPS software and the true locations should be as little as possible.
The amount of internal leakage at all potential locations between cylinder and valve and its
dependency on steering pressure should be as little as possible.
The amount of backlash in the feedback signal. Extreme care must be taken when an actuator
position sensor is installed.
The controller has proofed repeatable steady state accuracy at ± 1% of the full control region.
Proportional Band
In order to acquire open loop steering characteristics like absences of stability problems and lag, the
available proportional band for the controller is variable to steering wheel speed as shown in the figure
below.
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Steering by Steering Wheel – Closed Loop
Ql (Ff ) saturates
1000
900
Example
Off=300
Qm=900
Max port flow Ql (Ff )
800
700
defaults
Off=100
Qm=1000
600
Qm
500
400
300
Ql (Ff ) = |Ff| * 1.33+Off
200
100
0
Off
0
100
200
300
400
500
600
700
800
Ff - Feedforward
900 1000
P005 219E
Off Sets max port flow at zero feed forward. Setting the parameter equal to Qm disables the variable
proportional band.
The default value is set at 10% of max port flow, which is sufficient to counter act disturbances in steady
state and to control the steering actuator at low steering wheel speeds.
Qm Sets max port flow. It cuts-off the function and defines hereby the maximum speed of the steering
actuator to approach the set point position.
Kp This parameter is closely related to valve capacity, stroke volume and amplifies the error between setpoint and current position.
The optimum value for Kp is found when a non-lagging, accurate, non-oscillating steering actuation
without overshoot is achieved at:
•
•
Extreme low and high oil viscosities as specified in Technical Data on page 24.
Low and near max steering pressure when driving at low, high vehicle speed
and reversed gear. The default value fits to steering systems with a lock-tolock time of 2 seconds at max port flow.
Symbol
Index
Default
Value range
Kp
108
50
0 to 200 (0.00 to 2.00% of port flow capacity per 0.1 % positional error)
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Steering by Steering Wheel – Closed Loop
Symbol
Index
Default
Value range
Qm
1y27
1000
0 to 1000 (0.0 - 100.0% of max port flow)
Off
1y28
100
0 to 1000 (0.0 - 100.0% of max port flow)
StrkVol
707
600
10 to 8000 ccm
In order to ensure convergence, check that variable Yact is increasing for positive values of port flow.
Open loop control can be used to check this. To retrieve this data, use StartStopStatus and request status
data set number 2. See PVED-CL Communication Protocol. The PVED-CL will return the status data with ~
40 ms intervals.
This function will continuously minimize the steering wheel drift that is build up and which results in
misalignment of the straight direction indication on the steering wheel and the actual driving direction.
The absolute steering wheel sensor position 0 defines the straight direction. Aligning the steering wheel
sensor with straight driving direction can be achieved by orienting the SASA sensor to output position 0
when the steering wheel and steering actuator are in straight position. Alternatively the SASA sensor
position 0 can be programmed after physical installation. Refer to CAN message Protocol in OSPE Steering
Valve, SASA Sensor, Technical Information, 11068682.
Steering Wheel Knob Position Control
This function relates the absolute steering wheel position to the position of the steering actuator
What makes the steering wheel drift?
•
•
•
Flow & pressure saturation events that might occur during high steering wheel speeds combined
with low steering ratios.
Applying different steering ratios when driving into and out a curve. (Only when variable steering
ratio is active)
Activating joystick steering and re-activate steering wheel steering at a different actuator position
from where the joystick initially was activated.
Steering wheel drift is compensated by manipulation of the present steering sensitivity (Sts).
Kd Amplifies the steering wheel drift error. The resulting value represents a request in changing the
present steering sensitivity.
The default value disables the function.
Kc Limits the change in percentage of the present steering sensitivity.
The default value ensures that drift compensation is carried out beyond the notice of the driver.
Symbol
Index
Default
Value range
Kd
1y31
0
0 to 200
Kc
1y30
10
0 to 20 - > If Sts=400, Kc=10. Sts ranges from 360 to 440
Eliminate Noise due to Frequent Pressure Build-up
Eliminating noise is accomplished by stopping the controller to respond to minor deviations between set
point and current actuator position.
The spool inside the valve is set in neutral when the port flow command has been within a threshold
value (Qth) for a given time (Tclpout).
The spool is reactivated again when port flow command exceeds the threshold.
The default values mean that if a flow request from the controller is less than 5% of max. port flow, has
occurred for 3 seconds, the spool returns to neutral.
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Steering by Steering Wheel – Closed Loop
Tclpout Sets the time delay before the main spool is set in neutral.
Qth Sets the threshold value for port flow command when the controller is in steady state.
Symbol
Index
Default
Value range
Tclpout
117
3000
1 to 30 000 (ms)
Qth
118
50
0 to 100 (0.0 to 10.0 % of max port flow)
Magnetic Valve Control
Magnetic valves off delay time Disables the magnetic valve bridge after a time specified in ms when the
flow request is 0, otherwise it remains enabled. This parameter is used when electrical energy
consumption by the solenoid bridge in the PVED must be reduced or to remove a steering control
conflict between the OSP and the PVED.
This applies to the EHPS valve, where a conflict may happen if the PVED is configured to be controlled
with either CAN or analogue steering devices but not with the steering wheel angle signal. In this
configuration the PVED- has no information about the steering wheel operation cannot resolve the
conflict.
The default value disables this functionality i.e. the magnetic valve bridge is enabled at all times. The
magnetic valve bridge is enabled when the PVED-CL receives a non-zero flow request.
Use this parameter to create EHPS type 1 configurations.
Symbol
Index
Default
Value range
Magnetic valves off delay time
115
30 000
1 to 30 000 (ms)
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PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by High Priority Steering Device – Open Loop
Steering by High Priority Steering Device – Open Loop
EHPS Type 2 System Diagram
Joystick or mini wheel
High
priority
Steering angle sensor
OSP
OSP
Q
PVE EHPS
EHPS
valve
PVE
Valve
Q
Automatic steering
Steering
Steering
cylinder
cylinder
Position sensor
Vehicle speed
P005 225E
Functionality Tree
The tree below illustrates the availability of the PVED for steering by joystick, mini wheel with speed
output or by potentiometer-like steering devices. The manufacturing default functionality is found by
following the red line. Following the instructions in this chapter can of course modify the default. The
switches in the tree are used to select the functionality required. In case different functionalities are
required, the EHPS software provides 5 programs from which the driver can select when the system is
fully operative.
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switches
Sensitivity switch
*
Cp
Ramp switch
Control principle switch
Channel mapping switch
Steering by High Priority Steering Device – Open Loop
Sse
Sr
Fixed
Sse=1
Related to
position of
steering actuator
Sse=2
Open loop
Cp=0
Related to
vehicle speed
Sse=3
Program number: Y
Fixed
Sr=1
Var
Sr=2
No,
Sr=0
Fixed
Sr=1
Var
Sr=2
No,
Sr=0
Fixed
Sr=1
Var
Sr=2
No,
Sr=0
No signal (0)
Closed loop
Cp=255
CAN (255)
Fixed
Sse=1
Related to
vehicle speed
Sse=3
Y=0
Open loop, fixed sensitivity, with fixed ramp times,
1
2
3
4
Open loop, fixed sensitivity, with variable ramp
times as function to vehicle speed,
Open loop, fixed sensitivity, with no ramps
applied.
Open loop, sensitivity related to steering actuator
position, with fixed ramp times
Open loop, sensitivity as function to steering actuator
position, with variable ramp times related to vehicle
speed,
Open loop, sensitivity related to steering actuator
position, no ramps applied
Open loop, sensitivity related to vehicle speed,
with fixed ramp times
Open loop, sensitivity related to vehicle speed,
with ramp times related to vehicle speed
Open loop, sensitivity related to vehicle speed,
no ramp times applied
Closed loop, fixed sensitivity
Closed loop, sensitivity related to vehicle speed,
default
* Sensitivity means: number of revolutions on steering wheel from lock to lock
P005 202E
Select the Control Principle
The PVED-CL provides open loop control for steering devices with spring return or for steering devices
with a speed output,. This control principle keeps a fixed or variable relation between steering input and
cylinder speed. The control loop provides several parameters to transform positional information to port
flow.
Cp selects the open-loop control using parameter index 3y02 equal to 0 (default). Y selects the program
and ranges from 0 and 9.
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Steering by High Priority Steering Device – Open Loop
SseSts0,Sts1,Sts2,
Sts3,Sts4,Sts5, Vesm
100 ms
Ve -Vehicle
speed
10 ms
Yact - Actuator
position
10 ms
Xstl - Joystick
signal
Sr, Lr, Tro, Tfo, Lf,
Trh, Tfh, YsetFr, Tfr,
TAbortDownRamp,
Tra, Verm
Steering
sensitivity
Cf, Off
Yr,Yl
Ramp
function
Transfer
function
Soft
stop
Ve
Vehicle 100 ms
speed
Qm,Lx,db
Q
Port flow
command
Yact
Actuator 10 ms
position
P005 207E
Acquire the Signals
See Mapping a Steering Device on page 34 on how to map the steering wheel sensor and steering wheel
angle sensor.
Set-point Transfer Function
The transfer function provides 3 parameters to transfer joystick inputs signal to requested port flow.
1000
CR - port
Max input signal
for activating the
steering device
into the left
direction or
CCW
Qr - requested port flow: 1
unit = 0.1% of Max port flow
Example
db=100, Lx=10
Qm= -750
Sts=116
-1000
-750
-500
Saturation
750
500
Qm
Lx
250
250
-250
-250
Max input signal
for activating the
steering device
into the right
direction or CW
Sts
500
750
1000
Xstl - input signal:
1 unit = 0.1% of
Max activation
db
-500
Defaults
db=50, Lx=0
Qm =1000
Sts=105
Saturation
-750
-1000
CL - port
P005 210E
Db Sets a dead-band in the middle region of the steering input. It prevents self-steering caused by
manufacturing deviations in the signal when the handle is in the middle or released position.
The default value is set twice the maximum deviation of most spring returned steering devices.
Lx Effect the inherent linearity between steering actuator speed and steering angle. The set value is set
down when slower cylinder speed at larger steering angles is required.
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The default value will not effect the resulting relation.
Qm Limits the maximum cylinder speed for steering the vehicle in the right steering direction. (See setpoint transfer function above)
The default value is set equal to the inherent max port flow capacity of the valve and will therefore not
have any effect.
Symbol
Index
Default
Value range
db
3y05
50
0 to 250
Lx
3y06
0
-10 (max regressive), 0 (linear) to 10 (max progressive)
Qm
3y27
1000
0 to 1000 (100% flow at CR- or CL-port
Steering Sensitivity
Sensitivity is set individually for each program and can be either fixed or variable. Variability can depend
on vehicle speed, steered wheel position, or change of current device program.
Using variable sensitivity can increase comfort and drivability significantly, and depending on the vehicle
type and use the appropriate way to achieve the change might be different.
The PVED-CL allows several programs for each steering device, which means that 5 to 10 different
programs with different sensitivity settings can be made and applied via the MMI while driving. Each
program can then use either fixed or variable sensitivity – hence we talk ‘second-order-variability’ by
using the PVED-CL.
Max Sts = 1200
Vesm = 500
Vehicle speed dependant
(linear) – program 1
420
Vehicle speed dependant
(non-linear) – program 2
400
Fixed sensitivity – program 0
380
Vehicle speed dependant
(non-linear) – program 3
360
Sts5
Sts4
Sts3
Sts0
Sts1
Sts2
340
Min Sts = 20
0
100
200
300
400
500
600
700
Ve = Vehicle speed: 1 unit = 0.1 km/h
800
900
1000
Vehicle speed
Select a Fixed Sensitivity
A fixed steering sensitivity is chosen when no cylinder position or vehicle speed signal is available on the
vehicle.
Sse Selects between a fixed steering sensitivity, variable to steering actuator position or vehicle speed.
Set Sse to 1 to select the fixed sensitivity.
Sts0 Sets a gradient between steering angle and requested port flow. Sts0 is normally set when max port
flow (defined by Qm) is achieved at maximum steering device input. This is calculated by the following
function.
Qm • 100
Sts = ________
1000-db
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The default value is a gradient matching maximum requested port flow to maximum port flow at the
maximum steering angle.
Symbol
Index
Default
Value range
Sse
3y09
1
Must be set at 1
Sts0
3y10
105
20 to 1200 (Amplification of 0.2 to 12.00)
Select a Sensitivity with Relation to the Actuator Position
A steering sensitivity related to actuator position is normally chosen for increased directional stability for
straightforward driving (material handling). The values & correlation is normally closely related to the
mechanical geometry between steering actuator and steered wheels of the individual vehicle. The
correlation is defined by 2 parameters. The steering sensitivity between two table coordinates is found by
linear interpolation. The relation is equal for negative positions.
Sts(Yact) saturates
120
100
80
End lock position
Steering sensitivity Sts (Yact)
max Sts = 1200
60
Straight forward
driving position
40
min Sts = 20
0
100
200
300
400
500
600
700
800
900 1000
Yact - Steering actuator position: 1 unit = 0.1% of max position
P005 098E
Sse Selects between a fixed steering sensitivity, variable to steering actuator position or vehicle speed.
Set Sse to 2 to select the sensitivity related to steering actuator position.
Sts0 Sets the linear gradient between steering angle and requested port flow for steering
straightforward. When the steering actuator signal unintentionally is not mapped, Sts0 will be constantly
used since variable Yact remains 0.
Sts1 Sets the linear gradient between steering angle and requested port flow for steering at the
minimum turning radius.
Symbol
Index
Default
Value range
Sse
3y09
1
Must be set at 2
Sts0
3y10
105
20 to 1200 (Amplification of 0.2 to 12.00)
Sts1
3y11
90
20 to 1200
See chapter Mapping steering signals, Steering actuator Sensor (feedback from vehicle wheels) and Steering actuator position to acquire “steering
actuator position”.
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Select a Sensitivity with Relation to Vehicle Speed
Variable steering sensitivity related to vehicle speed is normally used to optimize directional stability
automatically and beyond the notice of the driver. The values and correlation is normally closely related
to the present vehicle dynamics of the individual vehicle model. The Sts value is used to amplify the input
signal as described in Set-point Transfer Function on page 44 .
The correlation is defined by seven parameters. All Sts-parameters may be set equal to each other or set
monotonically falling for increasing vehicle speeds. The steering sensitivity between two table
coordinates is found by linear interpolation. The relation is equal for negative speeds.
max Sts = 1200
Steering sensitivity Sts
(Ve)
120
Sts0=105
100
Sts1=90
80
Vesm=500
Sts2=75
Sts3=60
60
Sts (Ve) saturates
Sts4=45
40
min Sts = 20
Sts5=30
0
100
200
300
400
500
600
700
800
900 1000
Ve - Vehicle speed: 1 unit = 0.1 km/h
P005 088E
Sse Selects between a fixed steering sensitivity, variable to steering actuator position or vehicle speed.
Set Sse to 3 to select the sensitivity related to vehicle speed.
Sts0 Sets the linear gradient between steering angle and requested port flow when the vehicle is
standing still. When the vehicle signal unintentionally not is mapped, Sts0 is applied constantly since
variable Ve remains 0. In case the vehicle signal not is diagnosed, it is recommended to set Sts0 at a value
where sufficient directional stability at maximum vehicle speed is present.
Sts1 Sets the linear gradient between steering angle and requested port flow when the vehicle is driving
at 6.25% of the speed defined by parameter Vesm.
Sts2 Sets the linear gradient between steering angle and requested port flow when the vehicle is driving
at 12.50% of the speed defined by parameter Vesm.
Sts3 Sets the linear gradient between steering angle and requested port flow when the vehicle is driving
at 25.00% of the speed defined by parameter Vesm.
Sts4 Sets the linear gradient between steering angle and requested port flow when the vehicle is driving
at 50.00% of the speed defined by parameter Vesm.
Sts5 Sets the linear gradient between steering angle and requested port flow when the vehicle is driving
at 100.00% of the speed defined by parameter Vesm.
Vesm Sets the region where steering sensitivity is variable to vehicle speed.
Symbol
Index
Default
Value range
Sse
3y09
1
Must be set at 3
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Steering by High Priority Steering Device – Open Loop
Symbol
Index
Default
Value range
Sts0
3y10
105
20 to 1200 (Amplification of 0.2 to 12.00)
Sts1
3y11
90
20 to Sts0
Sts2
3y12
75
20 to Sts1
Sts3
3y13
60
20 to Sts2
Sts4
3y14
45
20 to Sts3
Sts5
3y15
30
20 to Sts4
Vesm
3y16
500
1 (0.1 km/h) to 1000 (100.0 km/h)
Please note the parameter dependency of Sts. See Mapping steering signals and J1939 Vehicle Speed to acquire “ Vehicle speed”
Ramps (Anti-Jerk)
Ramps are normally used to minimize jerk forces in machines with articulated steered steering systems. In
these steering systems, the articulating masses can be instantly stopped by closing the valve oil flow. An
instant cylinder movement stop starts the articulating masses to oscillate until all kinetic energy is
dispatched into heat by the shock valves or by the friction between wheels and ground. Jerk is an
inherent characteristic of articulated steered vehicles and cannot be completely removed. However, it is
best minimized when the forces are monotonically reduced in magnitude.
To achieve this, the EHPS software provides linear or non-linear ramps which in effect creates an orifice
across the main spool to tank by holding the valve open near its closing position until all kinetic energy is
dispatched into heat for some time. Ramps work on the valve spool set-point.
Sr sets the method. The ramp times can be disabled, fixed or related to vehicle speed. Set Sr to 0 to select
no ramps (Default), 1 to select fixed ramp times, or 2 for speed dependent ramp times.
Symbol
Index
Default
Value range
Sr
3y17
0
Must be set at 0
The below figure shows the operation of ramps with fixed ramp times and illustrates different ramp
scenarios. Qr is the request port flow commanded with the high priority steering device. Qramp the ramp
limited port flow and can be regarded as the result of the ramp function.
Qr, Qramp
Qr Requested port flow
Qramp ramp port flow
YsetFr
YAbortDownRamp
1 unit = 0.1% of max. port flow
1000
YsetFr, fast ramp down range
750
500
slow ramp down range
250
YAbortDownRamp
0
-250
-500
-750
Tfr
Tro
Tfo
Up ramp
Slow down ramp
}
Abort down ramp
time
}
Slow down ramp
-YsetFr
-1000
}
Fast down ramp
P005 205E
Sr Selects the ramp type. The ramp function can be disabled, fixed or related to vehicle speed. Set Sr to 1
to select fixed ramps.
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Lr Sets the linearity of the ramp-up curve.
The default value is a linear ramp.
Lf Sets the linearity of the slow ramp-down curve.
The default value is a linear ramp.
Select Ramps with Fixed Ramp Times
Tro Sets the ramp-up time to open the valve from zero to max port flow. The time applies for both ports.
To gain the best performance, the ramp-up time shall be set larger than the inherent ramp up time of the
main spool. See Technical Data on page 24.
Tfo Sets the ramp-down time to close the valve from max to zero port flow. The time applies for both
ports. It has most effect when the ramp-up time is set larger than the inherent ramp down time of the
main spool. See Technical Data on page 24.
YsetFr Experience shows that ramping down from maximum flow towards medium flows do not cause
as much jerk as ramping down from medium flows towards no flow (close to the valve dead-bands). In
order to “expedite” the ramping at large flows, a flow range can be set up where the spool can move
faster down to a flow range, where the slow down ramp is active.
The overall goal with the parameter is to optimize steering response time without degrading the anti-jerk
performance. Set up fast ramp down time Tfr before tuning this parameter. Setting YsetFr to 1000
eliminates the effect of the fast ramp down. Typical settings are 500-800. Use trial and error.
Example:
A value of 800 can be interpreted as allowing the spool to ramp down with a fast ramp for flow requests
between maximum flow (1000) and 800/1000 of maximum flow.
Tfr This time defines the applied ramp time in the fast ramp-down range. It is defined as the ramp time
from maximum flow to no flow. This means that in practice, the actual fast ramp-down time is
proportional to the fast ramp-down range divided by 1000.
Use this optimization criterion: Ramp down as fast as possible for flow ranges, where jerks are not
significant. Typical values are 1-50 ms. The fast ramp down time shall always be less than the slow rampdown time. Once the value is set, it should not be adjusted anymore during further ramp parameter
optimization.
YAbortDownRamp To come around the problem of slow steering response for large down-ramp times,
especially if a sudden emergency change of direction is needed, a slow down-ramp can be aborted by
requesting a flow in the opposite direction. Once a slow down-ramp is aborted, an abort down-ramp
time, Tra is applied. Obviously Tra shall be significantly smaller than the slow down-ramp to get any
effect.
Tra is the ramp-down time applied when the slow down-ramp is aborted. This rampdown time shall
typically be much lower than the slow ramp-down time, Tfo, in order to gain any increased steering
responsiveness. Typical value is half the value of Tfo or Tfh time if vehicle speed dependency is applied
(Sr=2). Use trail and error.
Example:
A value equal to 500 means that the driver needs to steer out 500/1000 of maximum flow before the slow
down-ramp is aborted. 500 again corresponds to a certain steering wheel RPM.
Typical values are 100-300 to have the abort down ramp possibility and to avoid unintentional abort of
the down ramp due to steering wheel activation due to vibrations. Setting the value to 1000 disables the
abort down ramp functionality.
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Steering by High Priority Steering Device – Open Loop
Symbol
Index
Default
Value range
Sr
3y17
0
Must be set at 1
Lr
3y19
0
0 (linear) to 10 (max progressive)
Lf
3y20
0
0 to 10
Tro
3y21
1
1 to 1000 (ms)
Tfo
3y23
350
1 to 1000 (ms)
YsetFr
3y32
1000
0 to 1000 (1 unit = 0.1% of max. flow)
Tfr
3y33
100
1 to 1000 ms
Tfr shall be smaller than Tfo and less than 150 ms.
YAbortDownRamp
3y34
0
0 to 500 (1 unit = 0.1% of max. flow).
The default value will force an down-ramp abort at a slight reverse port flow request.
Typically YAbortDownRamp needs be increased to avoid unintentional down-ramp
aborts as this will infer a jerk on the driver.
The discontinuities in the progressive characteristic are located at 50, 120 and 333 ([5.0;T at 25], [12,0;T at 50] and [33.3;T at 75] of max port flow
capacity)
Select Ramps with Ramp Time Related to Vehicle Speed
To optimize the anti-jerk performance to different work cycles, the vehicle speed can be used to derive
ramp times by interpolation between ramp values for 0 km/h.
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500
400
300
T(Ve) saturates
Default:
Verm=500
Tro=200
Trh=200
Tro
200
Trh
Verm
T(Ve) - Ramp up time in ms
max time = 1000
100
min time = 1
0
100
200
300
400
500
600
700
800
900 1000
Ve - Vehicle speed: 1 unit = 0.1 km/h
500
Default:
Verm=500
Tfo=350
Tfh=200
400
Tfo
300
T(Ve) saturates
Tfh
200
Verm
T(Ve) - Ramp down time in ms
max time = 1000
100
min time = 1
0
100
200
300
400
500
600
700
800
900 1000
Ve - Vehicle speed: 1 unit = 0.1 km/h
P005 218E
Sr Selects the ramp type. The ramp function can be disabled, fixed or related to vehicle speed. Set Sr to
21 to select vehicle speed dependant ramps.
Lr Sets the linearity of the ramp-up curve.
The default value is a linear ramp.
Lf Sets the linearity of the slow ramp-down curve.
The default value is a linear ramp.
Tro Sets the ramp-up time to open the valve from zero to max port flow when the vehicle speed is 0
kmph. The time applies for both ports.
To gain the best performance, the ramp-up time shall be set larger than the inherent ramp up time of the
main spool. See Technical Data on page 24.
Tfo Sets the ramp-down time to close the valve from max to zero port flow when the vehicle speed is 0
kmph. The time applies for both ports. It has most effect when the ramp-up time is set larger than the
inherent ramp down time of the main spool. See Technical Data on page 24 for these data.
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Steering by High Priority Steering Device – Open Loop
Trh Sets the ramp-up time to open the valve from zero to max port flow when the vehicle speed is equal
to Verm kmph. The time applies for both ports.
To gain the best performance, the ramp-up time shall be set larger than the inherent ramp up time of the
main spool. See Technical Data on page 24 for these ramp times.
Tfh Sets the ramp-down time to close the valve from max to zero port flow when the vehicle speed is
equal to Verm kmph. The time applies for both ports. It has most effect when the ramp-up time is set
larger than the inherent ramp down time of the main spool. See Technical Data on page 24 for these
ramp times.
Verm Sets the region (in kmph) where ramp-up (Trh) and ramp-down (Tfh) time is variable to vehicle
speed.
YsetFr Experience shows that ramping down from maximum flow towards medium flows do not cause
as much jerk as ramping down from medium flows towards no flow (close to the valve dead-bands). In
order to “expedite” the ramping at large flows, a flow range can be set up where the spool can move
faster down to a flow range, where the slow down ramp is active. The overall goal with the parameter is
too optimize steering response time without degrading the anti-jerk performance. Set up fast ramp down
time Tfr before tuning this parameter. Setting YsetFr to 1000 eliminates the effect of the fast ramp down.
Typical settings are 500-800. Use trial and error.
Example:
A value of 800 can be interpreted as allowing the spool to ramp down with a fast ramp for flow requests
between maximum flow (1000) and 800/1000 of maximum flow.
Tfr This time defines the applied ramp time in the fast ramp-down range. It is defined as the ramp time
from maximum flow to no flow. This means that in practice, the actual fast ramp-down time is
proportional to the fast ramp-down range divided by 1000.
Use this optimization criterion: Ramp down as fast as possible for flow ranges, where jerks are not
significant. Typical values are 1-50 ms. The fast ramp down time shall always be less than the slow rampdown time. Once the value is set, it should not be adjusted anymore during further ramp parameter
optimization.
YAbortDownRamp To come around the problem of slow steering response for large down-ramp times,
especially if a sudden emergency change of direction is needed, a slow down-ramp can be aborted by
requesting a flow in the opposite direction. Once a slow down-ramp is aborted, an abort down-ramp
time, Tra is applied. Obviously Tra shall be significantly smaller than the slow down-ramp to get any
effect.
Tra is the ramp-down time applied when the slow down-ramp is aborted. This rampdown time shall
typically be much lower than the slow ramp-down time, Tfo, in order to gain any increased steering
responsiveness. Typical value is half the value of Tfo or Tfh time if vehicle speed dependency is applied
(Sr=2). Use trail and error.
Example:
A value equal to 500 means that the driver needs to steer out 500/1000 of maximum flow before the slow
down-ramp is aborted. 500 again corresponds to a certain steering wheel RPM.
Typical values are 100-300 to have the abort down ramp possibility and to avoid unintentional abort of
the down ramp due to steering wheel activation due to vibrations. Setting the value to 1000 disables the
abort down ramp functionality.
Symbol
Index
Default
Value range
Sr
3y17
0
Must be set at 2
Lr
3y19
0
0 to 10 (linear to max progressive)
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Symbol
Index
Default
Value range
Lf
3y20
0
0 to 10
Tro
3y21
200
1 to 1000 ms
Tfo
3y23
350
1 to 1000 ms
Trh
3y22
200
1 to 1000
Tfh
3y24
350
1 to 1000
Verm
3y25
500
0 to 1000 (1 unit is 0.1 km/h)
YsetFr
3y32
1000
0 to 1000 (1 unit = 0.1% of max. flow).
Fast ramp-down is active in the port flow request range 1000 to YsetFr. The
default value disables fast ramp-down.
Tfr
3y33
100
1 to 1000 ms.
Tfr shall be smaller than Tfo and less than 150 ms.
YAbortDownRamp
3y34
0
0 to 500 (1 unit = 0.1% of max. flow).
The default value will force an down-ramp abort at a slight reverse port flow
request.
Typically YAbortDownRamp needs be increased to avoid unintentional
down-ramp aborts as this will infer a jerk on the driver.
The discontinuities in the progressive characteristic are located at 50, 120 and 333 ([5.0;T at 25], [12,0;T at 50] and [33.3;T at 75] of max port flow
capacity)
Anti-jerk Ramp Parameter Tuning Guide
Tuning the parameters is an iterative process. The following sequence may be useful when tuning a
vehicle:
1. Initial setting: Set Tro to 1. Tfr to 1. Set YsetFr to 1000. Set Tra to 1. Set YabortThreshold to 500.
2. Set the ramp-down time, Tfo, to a start value e.g. 500.
3. Decrease YsetFr from 1000 towards a smaller number. Observe which value of YsetFr where the level
of jerks starts to get worse to find the flow request range, where ramping has an effect. Optionally
increase Tfr to optimize on the fast ramp-down operation. Tfr should not exceed 150 ms and always
be smaller than Tfo.
4. Adjust the ramp-down time, Tfo, until at good anti-jerk performance is achieved.
5. Increase the ramp-up time, Tro, to further improve the anti-jerk performance. Tro is typically smaller
than Tfo.
6. Fine-tune the performance by experimenting with Tfr, Tra, and YsetFr. Note that the largest jerks shall
be tuned away with the ramp-up time, Tro, and ramp-down time, Tfo.
7. Finally the YAbortThrehold and Tra may be adjusted. Consider how many steering wheel RPM is
needed to abort the down-ramp. Secondly, adjust Tra to reduce the jerk when aborting the downramp. Obviously, Tra needs to be less than the down-ramp time, Tfo to get a faster steering response.
Typical values for Tra is 50 – 100 ms.
The above typical parameter settings may vary from vehicle to vehicle.
Soft (Cushion) End-stop
To prevent the steering actuator to hit the mechanical end lock with great speed, the PVED is able to slow
down the actuator speed when approaching the end lock electronically.
The red line in the figure below shows how the actuator is slowed down near the end lock position. The
black line in the figure below shows how port flow is reduced. The steering actuator signal must be
present in the PVED for this functionality to work.
This functionality can be applied only in open-loop control mode, but requires that a steered wheel
feedback sensor is mapped and mounted on either the steered wheel or cylinder, to indicate the motionrange.
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Steering by High Priority Steering Device – Open Loop
In the figure below the red line shows how the actuator is slowed down near the end lock position, and
the black line shows how port flow is reduced. The steering actuator signal must be present in the PVED
for this functionality to work.
Right end lock
1000
Cf
Yr, Software end lock position
500
Port flow
command
Steering actuator position
250
time
0
Off
Yact - steering actuator position
Q - port flow command
750
-250
Defaults
250 ms
Yl=-1000
-500
Yr=1000
-750
Cf=350
Off=50
-1000
Yl, Software end lock position
Left end lock
P005 221E
YR, YLThe difference between the values of both parameter set the freedom of the steering actuator.
Normally, YR is set equal at the right mechanical end lock. YL is normally set equal to the left mechanical
end lock. For example, setting YR at 500 and YL at –500 reduces the freedom of the actuator by 50%. The
default values for YR and YL are set equal to position of the mechanically end locks.
Cf Sets the region where actuation speed is slowed down. This region starts from the position defined by
YR and YL. Making this region to small reduces or can eliminate the effect of soft stop.
The default value for Cf ensures the valve is closed proportionally with actuator position.
Off This parameter sets the permitted actuation speed when hitting the end lock defined by YR or YL.
When the steering actuator passed YR or YL, actuation speed will decay to zero.
The default sets a speed that allows building up pressure when the actuator is located at YR or YL.
Symbol
Index
Default
Value range
YR
3y07
1000
-1000 – 1000, Values smaller than 0 will be set equal to the positive equivalent
YL
3y08
-1000
-1000 – 1000, Values greater than 0 will be set equal to the negative equivalent
Off
3y28
50
0 to 1000 (0.0 - 100.0% of max port flow)
Cf
3y29
333
1 to 1000
See chapter Mapping steering signals, Steering actuator Sensor (feedback from vehicle wheels) and Steering actuator position to acquire “steering
actuator position”.
Tolsout Maximum time where the main spool is allowed to be operated proportionally within the valve
dead-bands.
The main spool control range for this function can be seen in the Dead-band crossing on page 26.
This function is useful to eliminate frequent spool relocating events from its neutral to its dead-band
position and back (so called jumps) at small flow requests.
The flow request is 0 while moving the high priority steering device within the steering device deadband, db (see Set-point Transfer Function on page 44).
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Steering by High Priority Steering Device – Open Loop
Spool Dead-band Hold Control Function
Dead-band Jump Control
Set Tolsout lower than 21 (ms) to momentarily set the main spool in neutral as soon as the flow request is
0, No proportional spool movement will take place. The spool will jump from neutral to either of the valve
dead-bands depending on a flow request. The steering device dead-band, db, has no impact for these
Tolsout values.
Dead-band Hold and Proportional Control
Setting Tolsout between 21 and 30000 (ms) defines the maximum time where the main spool is either set
on the valve dead-band or controlled proportionally within the valve dead-band (granted that the flow
request is 0 during this time).
After a flow request to either left or right port, the main spool will be set on the respective left or right
valve dead-band. Any steering device movement within the defined steering device dead-band, db, will
result in proportional main spool movement. Proportional control will be allowed for Tolsout ms. If the
flow request has been 0 for Tolsout ms, the main spool will be set in neutral and any steering device
movements within db will be ignored.
To utilize proportional control, a steering device dead-band, db, needs to be created. If db is set a low
value, the main spool will effectively be operated as dead-band jump control.
Responding to Flow Requests after Tolsout
If the main spool has been set in neutral after Tolsout ms, any flow request will cause the spool to
immediately jump to the relevant spool position with no initial proportional dead-band control.
Symbol
Index
Default
Value range
Tolsout
316
10 000
1 to 30 000 (ms)
Magnetic Valves OFF Control
Magnetic valves off delay time disables the magnetic valve bridge after a time specified in ms when the
flow request is 0, otherwise it remains enabled. This parameter is used when electrical energy
consumption by the magnetic valve bridge in the PVED must be reduced or to resolve a steering control
conflict between the OSP and the PVED-CL (implementing EHPS type 1 systems only).
The default value disables this functionality i.e. the magnetic valve bridge is enabled at all times. The
magnetic valve bridge is enabled when the PVED-CL receives a non-zero flow request.
Symbol
Index
Default
Value range
Magnetic valves Off delay time
315
30 000
1 to 30 000 (ms)
Resolving a Steering Control Conflict
On systems utilizing a PVED-CL, an EHPS valve, an OSP, a CAN or analogue steering device but no
steering wheel angle sensor (SASA) (EHPS type 1), the PVED-CL has no means to detect that the steering
wheel is being activated. A steering conflict between OSP steering and steering device steering is thus
possible.
To resolve this conflict, set Tolsout to a value (typically 50 ms – 200 ms) to disable the magnetic valve
bridge when no flow request is being commanded with the steering device.
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Steering by High Priority Steering Device – Closed Loop
Steering by High Priority Steering Device – Closed Loop
EHPS Type 2 Automatic Steering Diagram
Joystick or mini wheel
High
priority
Steering angle sensor
OSP
OSP
Q
PVE EHPS
EHPS
valve
PVE
Valve
Q
Automatic steering
Steering
Steering
cylinder
cylinder
Position sensor
Vehicle speed
P005 225E
Functionality Tree
The tree below illustrates the functionality available in the PVED for steering by a potentiometer device
or by joystick or by mini wheel with speed output. The manufacturing default functionality is found by
following the red line. It can of course be modified by following the instructions in this chapter. The
switches in the tree are used to select the functionality required. In case different functionalities are
required, the EHPS software provides 5 programs from which the driver can select when the system is
fully operative. For steering by a device without spring return the PVED provides closed loop position
control. The steering signal is monotonic and represents the angle of the physical device. These devices
are normally friction held to prevent unintentionally steering due to machine vibrations. Use this mode
for implementation of proprietary auto-guidance applications i.e. auto-guidance applications that do not
conform to the ISO standardized auto-guidance messages. See Auto-steering on page 105.
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Switches
Control principle switch
*
Cp
Ramp switch
Sensitivity switch
Channel mapping switch
Steering by High Priority Steering Device – Closed Loop
Sse
Program number: Y
Sr
Fixed Sr=1
Var Sr=2
Open loop, fixed sensitivity, with fixed ramp
times
Open loop, fixed sensitivity, with ramp times
related to vehicle speed
Y=0
1
2
3
4
No Sr=0
Open loop, fixed sensitivity, with no
ramps applied
Fixed
Sse=1
Related to
position of
steering
actuator
Sse = 2
Related to
vehicle speed
Sse=3
Open loop
Cp=0
Fixed Sr=1
Var Sr=2
No Sr=0
Fixed Sr=1
Var Sr=2
No Sr=0
No signal (0)
AD1 (1)
AD2 (2)
CAN (4)
Open loop, sensitivity related to steering actuator
position, with fixed ramp times
Open loop, sensitivity related to steering actuator
position, with ramp times related to vehicle speed
Open loop, sensitivity related to steering actuator
position, with no ramps applied
Open loop, sensitivity related to vehicle speed, with
fixed ramp times
Open loop, sensitivity related to vehicle speed, with
ramp times related to vehicle speed
Open loop, sensitivity related to vehicle speed,
with no ramps applied
Closed loop
Cp=255
Closed loop, Fixed sensitivity, no ramps possible
default
* Sensitivity means: Port flow amplification
P005 089E
Tracking
For safety reasons, a tracking function ensures bump-less transition on control loop initialization. It forces
the user initially to operate the potentiometer knob into a position that matches zero deviation between
set point and current steering actuator position or by sweeping through it. While tracking, the
commanded port flow is limited at zero.
Yr, Yl, Lx, Xysat, db
10 ms
Xstl Potmeter
like
device
Angle
Qm
Kp
Setpoint
Port flow
limiter
Tracking
Q - Port flow
command
10 ms
Yact Actuator
position
P005 211E
Select the Control Principle
Cp selects the closed loop control using parameter index 3y02 equal to 255. Y selects the program and
ranges from 0 and 4. The value for y must be consistently used throughout the entire configuration of a
single program.
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Steering by High Priority Steering Device – Closed Loop
Acquire the Signals
See Mapping a Steering Device on page 34 on how to map an analogue or CAN-based high priority closedloop steering device and steering wheel angle sensor.
Create the Set Point
Steering actuator
position setpoint
Example:
db = 250, Lx = 10
Xysat = 750
YR = -750
YL = 500
1000
YL
750
500
250
Max input signal
for activating the
steering device
into the left
-1000
direction
-750
-500
-250
Defaults:
db = 0, Lx = 0
Xysat = 1000
YR = 1000
YL = -1000
saturation
-500
-750
Lx
YR
db
250
-250
Xysat
500
750
1 unit = 0.1% of
steering actuator at the
left end lock position
Right steering
actuator end-lock
1 unit = 0.1% of
steering actuator at the
right end lock position
A function provides 5 parameters to transform angle information to a steering actuator position set point.
-1000
Max input signal
for activating the
steering idevice
into the right
direction
1000
Xstl - Input signal: 1
unit = 0.1% of max
activation
Left steering
actuator end- lock
P005 212E
db Sets a dead band about the middle region of the signal. The parameters prevent self-steering, caused
by manufacturing deviations in the signal when the handle is in the middle or released position.
However, db is normally set to zero for pot-meter like steering devices.
The default value is set to serve pot-meter like steering devices
Lx Set the curve linearity. The parameter is set down when the cylinder position is too far (over-steer) for
small steering angles or vice versa.
The optimum value for this parameter is closely related to:
•
•
•
•
The inherent linearity between steering actuator position and signal
The inherent linearity between device handle angle and signal
The inherent over or under-steer tendency of the vehicle when steering into curves
The default value will not effect the resulting relation.
YR, YL The difference between the values of both parameter set the freedom of the steering actuator.
Normally, YR is set equal at the right mechanical end lock. YL is normally set equal to the left mechanical
end lock. This results in steering to the right direction. In case an opposite steering behavior is required,
YR must be set at the negative equivalent and YL must be set at the positive equivalent
(See example). The default value for YR and YL is set equal to the mechanical locks of the steering
actuator resulting in the vehicle to steer in the right direction.
Yxsat Sets a threshold for the output to be at its maximum or minimum when the input signal exceeds
the threshold value. Yxsat is normally set down when more sensitivity is required than inherently
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Steering by High Priority Steering Device – Closed Loop
available with the steering device. The default value will not effect the inherent sensitivity of the steering
device.
Symbol
Index
Default
Value range
db
3y05
0
0.0 to 250 (0.0 to 25.0% of max activation in the right steering direction)
Lx
3y06
0
-10 to 10 (-10 max regress, 0 linear, 10 max progress)
YR
3y07
1000
-1000 to 1000
YL
3y08
-1000
-1000 to 1000
Yxsat
3y03
1000
251 to 1000
Parameter Yxsat, db & Lx have same value in quadrant 2 & 3. Lx in quadrant 1 or 4 is located at: [(Xysat+db)/2; YR*(20-Lx)/40]. Lx in quadrant 2 or 3 is
located at: [-(Xysat+db)/2; YL*(20-Lx)/40].
Closing the Loop
Kp Amplifies the error between set point and current position. The optimum value for Kp is found when a
non-lagging, accurate, non-oscillating steering actuation without overshoot is achieved at extreme low
and high oil viscosities as specified in chapter: (robustness to changes sin dead times) and at low and
near max steering pressure when driving at low, high vehicle speed and reversed gear (robustness to
changes in damping & dead times). Moreover, Kp is closely related to valve capacity, stroke volume. See
section Steady State Error on page 61 for information on accuracy. The default value fits to steering
systems with a lock-to-lock time of 2 seconds at max port flow.
Qm Sets the maximum port flow. It effects the speed of the steering actuator to move towards the set
point position. Negative values of Qm are interpreted as the positive equivalent.
The default value is set equal to the inherent max port flow capacity of the valve and will therefore not
have any effect.
Symbol
Index
Default
Value range
Kp
308
50
0 to 200 (0.00 to 2.00% of port flow capacity of the valve for 0.1% positional
error)
Qm
3y27
1000
0 to 1000 (0.0 to 100.0 % port flow)
Eliminate Noise due to Frequent Pressure Build-up
Eliminating noise is accomplished by stopping the controller to respond to minor deviations between set
point and current actuator position. The spool inside the valve is set in neutral when the port flow
command has been within a threshold value (Qth) for a given time (Tclpout). The spool is reactivated
again when port flow command exceeds the threshold.
Tclpout Sets the time delay (ms) before the main spool is set in neutral.
Qth Sets the threshold value for port flow command when the controller is in steady state.
Symbol
Index
Default
Value range
Tclpout
317
3000
1 to 30000 (ms)
Qth
318
50
0 to 100 (0.0 to 10.0% of max port flow)
Magnetic Valves OFF Control
Magnetic valves off delay time Disables the magnetic valve bridge after a time specified in ms when the
flow request is 0, otherwise it remains enabled. This parameter is used when electrical energy
consumption by the magnetic valve bridge in the PVED must be reduced or to resolve a steering control
conflict between the OSP and the PVED-CL (implementing EHPS type 1 systems only).
The default value disables this functionality i.e. the magnetic valve bridge is enabled at all times. The
magnetic valve bridge is enabled when the PVED-CL receives a non-zero flow request
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Steering by High Priority Steering Device – Closed Loop
Symbol
Index
Default
Value range
Magnetic Valves Off delay time
315
30 000
1 to 30 000 (ms)
Resolving a Steering Control Conflict
On systems utilizing a PVED-CL, an EHPS valve, an OSP, a CAN or analogue steering device but no
steering wheel angle sensor (SASA) (EHPS type 1), the PVED-CL has no means to detect that the steering
wheel is being activated. A steering conflict between OSP steering and steering device steering is thus
possible. To resolve this conflict, set Tolsout to a value (typically 50 ms – 200 ms) to disable the magnetic
valve bridge when no flow request is being commanded with the steering device.
High Priority Steering Device Enable/Disable Control
The PVED functionality allows the user to dynamically enable or disable a steering device during
operation from the cabin MMI (via CAN bus). This functionality enables e.g. an armrest device to be
folded away for easy access to the cabin, while the system operational, to avoid the risk of unintended
device activation when the user enters or leaves the cabin.
Another user scenario is to disable one or more lower priority steering devices when only the steering
wheel device is in use for a longer period of time and the user wishes to eliminate the risk of
unintentional device activation.
System Requirements
The device enable/disable control functionality is only functional if the following conditions are fulfilled.
•
•
•
The system must be in operational state.
The device that shall be enabled/disabled is mapped.
An OSP for hydraulic backup exists and the presence of the OSP is configured in the PVED.
Symbol
Index
Default
Value range
HighPrioritySteeringDeviceInterface
65102
0
0 (NONE), 1 (AD1), 2 (AD2), 4 (CAN)
OSP present
65109
0
0 (NONE), 255 (PRESENT)
If an OSP is not present, the device enable/disable control command is ignored. The OSP shall be present
because it is theoretically possible to electrically disable all steering devices if the primary steering wheel
sensor is not mapped. In this situation only the OSP pilot signals are driving the valve.
C
Caution
The vehicle system integrator shall consider the following to ensure a safe and reliable device enable/
disable functionality:
•
•
•
•
It is recommended to include the vehicle velocity information in the decision whether a device
disable request shall be sent to the PVED or not.
The location of the enable/disable button shall be well-considered to avoid unintentional enabling/
disabling of a steering device.
Unintended enabling/disabling should be further avoided by requiring the enable/disable button to
be pressed for a well-defined period of time.
The OEM shall ensure that a steering device outputs a signal within a valid range when the device is
enabled.
Device Diagnostic Operation
The steering device diagnostic checks are performed both when the device is enabled and disabled.
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Steering by High Priority Steering Device – Closed Loop
Enable or Disable Joystick Steering Device
The device enable/disable control is executed by means of the DisableSteeringDevice command (see
PVED-CL Communication Protocol Technical Information, 11025584) from e.g. the man machine interface.
The DisableSteeringDevice command options are:
•
•
•
Arm joystick enable/disable
Enable joystick
Disable joystick
The enabling or disabling of a steering device must follow the state transition sequence shown below in
order to minimize undesired enabling or disabling of a steering device.
control byte = Arm device enable
Device enabled
armed
control byte = Enable device
timeout or incorrect control byte
Device disabled
Device enabled
timeout or incorrect control byte
control byte = Disable device
Device disabled
armed
control byte = Arm device disable
Disabled at power-up = FALSE
Disabled at power-up = TRUE
The states, device enabled armed and device disabled armed are volatile states. A transition from these
states to the desired state requires reception of a command message within 200 ms after the reception of
first command message. Otherwise the device disable state will change back to its last state.
Boot-up State of Steering Device
The boot-up enable/disable state of the device can be configured with a parameter and can be changed
via the SetParameter command (see PVED-CL Communication Protocol Technical Information, 11025584).
Symbol
Index
Default
Value range
HPStdDisabledAtBootUp
64008
0
0 (FALSE), 255 (TRUE)
HpStd means High Priority Steering Device.
If the device disable functionality is not desired, the parameter shall be 0.
Getting the Actual Enable/disable Status of the Device
The PVED will send one DisableSteeringDeviceResponse reply message to each DisableSteeringDevice
command it receives (or on time-out), containing the present enable/disable state for all steering devices.
This reply may be used by the MMI for acknowledge or display purposes (see PVED-CL Communication
Protocol Technical Information, 11025584).
The device enable/disable present status for all devices is also transmitted periodically in the
OperationStatus message which is transmitted on the CAN bus by default (see PVED-CL Communication
Protocol Technical Information, 11025584).
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Steering by Low Priority Steering Device – Open Loop
Steering by Low Priority Steering Device – Open Loop
EHPS Type 2 System Diagram
Joystick or mini wheel
Low
priority
Steering angle sensor
OSP
OSP
Q
PVE EHPS
PVE
Valve
EHPS
valve
Q
Automatic steering
Steering
Steering
cylinder
cylinder
Position sensor
Vehicle speed
Functionality Tree
The tree below illustrates the availability of the PVED for steering by joystick, mini wheel with speed
output or by potentiometer-like steering devices. The manufacturing default functionality is found by
following the red line. Following the instructions in this chapter can of course modify the default. The
switches in the tree are used to select the functionality required. In case different functionalities are
required, the EHPS software provides 5 programs from which the driver can select when the system is
fully operative.
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Control principle switch
*
Cp
Switches
Ramp switch
Sensitivity switch
Channel mapping switch
Steering by Low Priority Steering Device – Open Loop
Sse
Program number: Y
Sr
Fixed Sr=1
Var Sr=2
Open loop, fixed sensitivity, with fixed ramp
times
Y=0
1
2
3
4
Open loop, fixed sensitivity, with ramp times
related to vehicle speed
No Sr=0
Open loop, fixed sensitivity, with no
ramps applied
Fixed
Sse=1
Related to
position of
steering
actuator
Sse = 2
Related to
vehicle speed
Sse=3
Open loop
Cp=0
Fixed Sr=1
Var Sr=2
No Sr=0
Fixed Sr=1
Var Sr=2
No Sr=0
No signal (0)
AD1 (1)
AD2 (2)
CAN (4)
Open loop, sensitivity related to steering actuator
position, with fixed ramp times
Open loop, sensitivity related to steering actuator
position, with ramp times related to vehicle speed
Open loop, sensitivity related to steering actuator
position, with no ramps applied
Open loop, sensitivity related to vehicle speed, with
fixed ramp times
Open loop, sensitivity related to vehicle speed, with
ramp times related to vehicle speed
Open loop, sensitivity related to vehicle speed,
with no ramps applied
Closed loop
Cp=255
Closed loop, Fixed sensitivity, no ramps possible
default
* Sensitivity means: Port flow amplification
P005 099E
Select the Control Principle
The PVED-CL provides open loop control for steering devices with spring return or for steering devices
with a speed output,. This control principle keeps a fixed or variable relation between steering input and
cylinder speed. The control loop provides several parameters to transform positional information to port
flow.
Cp is used to select open loop control for joystick steering by setting parameter index 4y02 equal to 0.
Parameter selection values: Y selects the program and ranges from 0 and 9.
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Steering by Low Priority Steering Device – Open Loop
SseSts0,Sts1,Sts2,
Sts3,Sts4,Sts5, Vesm
100 ms
Ve -Vehicle
speed
10 ms
Yact - Actuator
position
10 ms
Xstl - Joystick
signal
Sr, Lr, Tro, Tfo, Lf,
Trh, Tfh, YsetFr, Tfr,
TAbortDownRamp,
Tra, Verm
Steering
sensitivity
Cf, Off
Yr,Yl
Ramp
function
Transfer
function
Soft
stop
Ve
Vehicle 100 ms
speed
Qm,Lx,db
Q
Port flow
command
Yact
Actuator 10 ms
position
P005 207E
Acquire the Signals
See Mapping a Steering Device on page 34 on how to map the steering wheel sensor and steering wheel
angle sensor.
Set-point Transfer Function
The transfer function provides 3 parameters to transfer joystick inputs signal to requested port flow.
1000
CR - port
Max input signal
for activating the
steering device
into the left
direction or
CCW
Qr - requested port flow: 1
unit = 0.1% of Max port flow
Example
db=100, Lx=10
Qm= -750
Sts=116
-1000
-750
-500
Saturation
750
500
Qm
Lx
250
250
-250
-250
Max input signal
for activating the
steering device
into the right
direction or CW
Sts
500
750
1000
Xstl - input signal:
1 unit = 0.1% of
Max activation
db
-500
Defaults
db=50, Lx=0
Qm =1000
Sts=105
Saturation
-750
-1000
CL - port
P005 210E
Db Sets a dead-band in the middle region of the steering input. It prevents self-steering caused by
manufacturing deviations in the signal when the handle is in the middle or released position.
The default value is set twice the maximum deviation of most spring returned steering devices.
Lx Effect the inherent linearity between steering actuator speed and steering angle. The set value is set
down when slower cylinder speed at larger steering angles is required.
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The default value will not effect the resulting relation.
Qm Limits the maximum cylinder speed for steering the vehicle in the right steering direction. (See setpoint transfer function above)
The default value is set equal to the inherent max port flow capacity of the valve and will therefore not
have any effect.
Symbol
Index
Default
Value range
db
4y05
50
0 to 250
Lx
4y06
0
-10 (max regressive), 0 (linear) to 10 (max progressive)
Qm
4y07
1000
0 to 1000 (100% flow at CR- or CL-port
Steering Sensitivity
Sensitivity is set individually for each program and can be either fixed or variable. Variability can depend
on vehicle speed, steered wheel position, or change of current device program. Using variable sensitivity
can increase comfort and drivability significantly, and depending on the vehicle type and use the
appropriate way to achieve the change might be different.
The PVED-CL allows several programs for each steering device, which means that 5 to 10 different
programs with different sensitivity settings can be made and applied via the MMI while driving. Each
program can then use either fixed or variable sensitivity – hence we talk ‘second-order-variability’ by
using the PVED-CL.
Max Sts = 1200
Vesm = 500
Vehicle speed dependant
(linear) – program 1
420
Vehicle speed dependant
(non-linear) – program 2
400
Fixed sensitivity – program 0
380
Vehicle speed dependant
(non-linear) – program 3
360
Sts5
Sts4
Sts3
Sts0
Sts1
Sts2
340
Min Sts = 20
0
100
200
300
400
500
600
700
Ve = Vehicle speed: 1 unit = 0.1 km/h
800
900
1000
Vehicle speed
Select a Fixed Sensitivity
A fixed steering sensitivity is chosen when no cylinder position or vehicle speed signal is available on the
vehicle.
Sse Selects between a fixed steering sensitivity, variable to steering actuator position or vehicle speed.
Set Sse to 1 to select the fixed sensitivity
Sts0 Sets a gradient between steering angle and requested port flow. Sts0 is normally set when max port
flow (defined by Qm) is achieved at maximum steering device input. This is calculated by the following
function.
Qm • 100
Sts = ________
1000-db
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Steering by Low Priority Steering Device – Open Loop
The default value is a gradient matching maximum requested port flow to maximum port flow at the
maximum steering angle.
Symbol
Index
Default
Value range
Sse
4y09
1
Must be set at 1
Sts0
4y10
105
20 to 1200 (Amplification of 0.2 to 12.00)
Select a Sensitivity with Relation to the Actuator Position
A steering sensitivity related to actuator position is normally chosen for increased directional stability for
straightforward driving (for e.g. material handling). The values and correlation is normally closely related
to the mechanical geometry between steering actuator and steered wheels of the individual vehicle.
The correlation is defined by two parameters. The steering sensitivity between two table coordinates is
found by linear interpolation. The relation is equal for negative positions.
Sts(Yact) saturates
120
100
80
End lock position
Steering sensitivity Sts (Yact)
max Sts = 1200
60
Straight forward
driving position
40
min Sts = 20
0
100
200
300
400
500
600
700
800
900 1000
Yact - Steering actuator position: 1 unit = 0.1% of max position
P005 098E
Sse selects between a fixed steering sensitivity, variable to steering actuator position or vehicle speed.
Set Sse to 2 to select the sensitivity related to steering actuator position
Sts0 sets the linear gradient between steering angle and requested port flow for steering
straightforward. When the steering actuator signal unintentionally is not mapped, Sts0 will be constantly
used since variable Yact remains 0.
Sts1 sets the linear gradient between steering angle and requested port flow for steering at the
minimum turning radius.
Symbol
Index
Default
Value range
Sse
4y09
1
Must be set at 2
Sts0
4y10
105
20 to 1200 (Amplification of 0.2 to 12.00)
Sts1
4y11
90
20 to 1200
See chapter Mapping steering signals, Steering actuator Sensor (feedback from vehicle wheels) and Steering actuator position to acquire “steering
actuator position”.
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Select a Sensitivity with Relation to Vehicle speed
Variable steering sensitivity related to vehicle speed is normally used to optimize directional stability
automatically and beyond the notice of the driver. The values and correlation is normally close related to
the present vehicle dynamics of the individual vehicle model. The Sts value is used to amplify the input
signal as described in Set-point Transfer Function on page 87.
The correlation is defined by seven parameters. All Sts-parameters may be set equal to each other or set
monotonically falling for increasing vehicle speeds. The steering sensitivity between two table
coordinates is found by linear interpolation. The relation is equal for negative speeds.
max Sts = 1200
Steering sensitivity Sts
(Ve)
120
Sts0=105
100
Sts1=90
80
Vesm=500
Sts2=75
Sts3=60
60
Sts (Ve) saturates
Sts4=45
40
min Sts = 20
Sts5=30
0
100
200
300
400
500
600
700
800
900 1000
Ve - Vehicle speed: 1 unit = 0.1 km/h
P005 088E
Sse Selects between a fixed steering sensitivity, variable to steering actuator position or vehicle speed.
Set Sse to 3 to select the sensitivity related to vehicle speed.
Sts0 Sets the linear gradient between steering angle and requested port flow when the vehicle is
standing still. When the vehicle signal unintentionally not is mapped, Sts0 is applied constantly since
variable Ve remains 0. In case the vehicle signal not is diagnosed, it is recommended to set Sts0 at a value
where sufficient directional stability at maximum vehicle speed is present
Sts1 Sets the linear gradient between steering angle and requested port flow when the vehicle is driving
at 6.25% of the speed defined by parameter Vesm.
Sts2 Sets the linear gradient between steering angle and requested port flow when the vehicle is driving
at 12.50% of the speed defined by parameter Vesm.
Sts3 Sets the linear gradient between steering angle and requested port flow when the vehicle is driving
at 25.00% of the speed defined by parameter Vesm.
Sts4 Sets the linear gradient between steering angle and requested port flow when the vehicle is driving
at 50.00% of the speed defined by parameter Vesm.
Sts5 Sets the linear gradient between steering angle and requested port flow when the vehicle is driving
at 100.00% of the speed defined by parameter Vesm.
Vesm Sets the region where steering sensitivity is variable to vehicle speed.
Symbol
Index
Default
Value range
Sse
4y09
1
Must be set at 3
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PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Operation Manual
Steering by Low Priority Steering Device – Open Loop
Symbol
Index
Default
Value range
Sts0
4y10
105
20 to 1200 (Amplification of 0.2 to 12.00)
Sts1
4y11
90
20 to Sts0
Sts2
4y12
75
20 to Sts1
Sts3
4y13
60
20 to Sts2
Sts4
4y14
45
20 to Sts3
Sts5
4y15
30
20 to Sts4
Vesm
4y16
500
1 (0.1 km/h) to 1000 (100.0 km/h)
Please note the parameter dependency of Sts.
See Mapping steering signals and J1939 Vehicle Speed to acquire “ Vehicle speed”
Ramps (Anti-jerk)
Ramps are normally used to minimize jerk forces in machines with articulated steered steering systems. In
these steering systems, the articulating masses can be instantly stopped by closing the valve oil flow. An
instant cylinder movement stop starts the articulating masses to oscillate until all kinetic energy is
dispatched into heat by the shock valves or by the friction between wheels and ground. Jerk is an
inherent characteristic of articulated steered vehicles and cannot be completely removed. However, it is
best minimized when the forces are monotonically reduced in magnitude.
To achieve this, the EHPS software provides linear or non-linear ramps which in effect creates an orifice
across the main spool to tank by holding the valve open near its closing position until all kinetic energy is
dispatched into heat for some time. Ramps work on the valve spool set-point.
Sr sets the method. The ramp times can be disabled, fixed or related to vehicle speed. Set Sr to:
•
•
•
0 to select no ramps (default),
1 to select fixed ramp times, or
2 for speed dependent ramp times.
The figure below shows the operation of ramps with fixed ramp times and illustrates different ramp
scenarios. Qr is the request port flow commanded with the steering wheel. Qramp the ramp limited port
flow and can be regarded as the result of the ramp function.
Qr, Qramp
Qr Requested port flow
Qramp ramp port flow
YsetFr
YAbortDownRamp
1 unit = 0.1% of max. port flow
1000
YsetFr, fast ramp down range
750
500
slow ramp down range
250
YAbortDownRamp
0
-250
-500
-750
Tfr
Tro
Tfo
Up ramp
Slow down ramp
}
Abort down ramp
time
}
Slow down ramp
-YsetFr
-1000
}
Fast down ramp
P005 205E
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PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Low Priority Steering Device – Open Loop
Symbol
Index
Default
Value range
Sr
4y17
0
0 (default)
Ramps with Fixed Ramp Times
Sr Selects the ramp type. The ramp function can be disabled, fixed or related to vehicle speed. Set Sr to 1
to select fixed ramps.
Lr Sets the linearity of the ramp-up curve. The default value is a linear ramp.
Lf Sets the linearity of the slow ramp-down curve. The default value is a linear ramp.
Tro Sets the ramp-up time to open the valve from zero to max port flow. The time applies for both ports.
To gain the best performance, the ramp-up time shall be set larger than the inherent ramp up time of the
main spool.
See Technical Data on page 24 for these ramp times.
Tfo Sets the ramp-down time to close the valve from max to zero port flow. The time applies for both
ports. It has most effect when the ramp-up time is set larger than the inherent ramp down time of the
main spool.
See Technical Data on page 24 for these ramp times.
YsetFr Experience shows that ramping down from maximum flow towards medium flows do not cause
as much jerk as ramping down from medium flows towards no flow (close to the valve dead-bands). In
order to “expedite” the ramping at large flows, a flow range can be set up where the spool can move
faster down to a flow range, where the slow down ramp is active. The overall goal with the parameter is
too optimize steering response time without degrading the anti-jerk performance. Set up fast ramp down
time Tfr before tuning this parameter. Setting YsetFr to 1000 eliminates the effect of the fast ramp down.
Typical settings are 500-800. Use trial and error.
Example:
A value of 800 can be interpreted as allowing the spool to ramp down with a fast ramp for flow requests
between maximum flow (1000) and 800/1000 of maximum flow.
Tfr This time defines the applied ramp time in the fast ramp-down range. It is defined as the ramp time
from maximum flow to no flow. This means that in practice, the actual fast ramp-down time is
proportional to the fast ramp-down range divided by 1000.
Use this optimization criterion: Ramp down as fast as possible for flow ranges, where jerks are not
significant. Typical values are 1-50 ms. The fast ramp down time shall always be less than the slow rampdown time. Once the value is set, it should not be adjusted anymore during further ramp parameter
optimization.
YAbortDownRamp To come around the problem of slow steering response for large down-ramp times,
especially if a sudden emergency change of direction is needed, a slow down-ramp can be aborted by
requesting a flow in the opposite direction. Once a slow down-ramp is aborted, an abort down-ramp
time, Tra is applied. Obviously Tra shall be significantly smaller than the slow down-ramp to get any
effect.
Tra is the ramp-down time applied when the slow down-ramp is aborted. This rampdown time shall
typically be much lower than the slow ramp-down time, Tfo, in order to gain any increased steering
responsiveness. Typical value is half the value of Tfo or Tfh time if vehicle speed dependency is applied
(Sr=2). Use trail and error.
Example:
A value equal to 500 means that the driver needs to steer out 500/1000 of maximum flow before the slow
down-ramp is aborted. 500 again corresponds to a certain steering wheel RPM.
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Low Priority Steering Device – Open Loop
Typical values are 100-300 to have the abort down ramp possibility and to avoid unintentional abort of
the down ramp due to steering wheel activation due to vibrations. Setting the value to 1000 disables the
abort down ramp functionality.
Symbol
Index
Default
Value range
Sr
4y17
0
Must be set at 1
Lr
4y19
0
0 (linear) to 10 (max progressive)
Lf
4y20
0
0 to 10
Tro
4y21
1
1 to 1000 (ms)
Tfo
4y23
350
1 to 1000 (ms)
YsetFr
4y32
1000
0 to 1000 (1 unit = 0.1% of max. flow)
Tfr
4y33
100
1 to 1000 ms
Tfr shall be smaller than Tfo and less than 150 ms.
YAbortDownRamp
4y34
0
0 to 500 (1 unit = 0.1% of max. flow).
The default value will force an down-ramp abort at a slight reverse port flow request.
Typically YAbortDownRamp needs be increased to avoid unintentional down-ramp
aborts as this will infer a jerk on the driver.
Tra
4y35
1
1 to 1000 ms
Ramp-down time for canceled down-ramp
The discontinuities in the progressive characteristic are located at 50, 120 and 333 ([5.0;T at 25], [12,0;T at 50] and [33.3;T at 75] of max port flow
capacity)
Select Ramps with Ramp Time Related to Vehicle Speed
To optimize the anti-jerk performance to different work cycles, the vehicle speed can be used to derive
ramp times by interpolation between ramp values for 0 km/h.
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Steering by Low Priority Steering Device – Open Loop
500
400
300
T(Ve) saturates
Default:
Verm=500
Tro=200
Trh=200
Tro
200
Trh
Verm
T(Ve) - Ramp up time in ms
max time = 1000
100
min time = 1
0
100
200
300
400
500
600
700
800
900 1000
Ve - Vehicle speed: 1 unit = 0.1 km/h
500
Default:
Verm=500
Tfo=350
Tfh=200
400
Tfo
300
T(Ve) saturates
Tfh
200
Verm
T(Ve) - Ramp down time in ms
max time = 1000
100
min time = 1
0
100
200
300
400
500
600
700
800
900 1000
Ve - Vehicle speed: 1 unit = 0.1 km/h
P005 218E
Sr Selects the ramp type. The ramp function can be disabled, fixed or related to vehicle speed. Set Sr to
21 to select vehicle speed dependant ramps.
Lr Sets the linearity of the ramp-up curve.
The default value is a linear ramp.
Lf Sets the linearity of the slow ramp-down curve.
The default value is a linear ramp.
Tro Sets the ramp-up time to open the valve from zero to max port flow when the vehicle speed is 0
kmph. The time applies for both ports.
To gain the best performance, the ramp-up time shall be set larger than the inherent ramp up time of the
main spool. See Technical Data on page 24.
Tfo Sets the ramp-down time to close the valve from max to zero port flow when the vehicle speed is 0
kmph. The time applies for both ports. It has most effect when the ramp-up time is set larger than the
inherent ramp down time of the main spool. See Technical Data on page 24 for these data.
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Low Priority Steering Device – Open Loop
Trh Sets the ramp-up time to open the valve from zero to max port flow when the vehicle speed is equal
to Verm kmph. The time applies for both ports.
To gain the best performance, the ramp-up time shall be set larger than the inherent ramp up time of the
main spool. See Technical Data on page 24 for these ramp times.
Tfh Sets the ramp-down time to close the valve from max to zero port flow when the vehicle speed is
equal to Verm kmph. The time applies for both ports. It has most effect when the ramp-up time is set
larger than the inherent ramp down time of the main spool. See Technical Data on page 24 for these
ramp times.
Verm Sets the region (in kmph) where ramp-up (Trh) and ramp-down (Tfh) time is variable to vehicle
speed.
YsetFr Experience shows that ramping down from maximum flow towards medium flows do not cause
as much jerk as ramping down from medium flows towards no flow (close to the valve dead-bands). In
order to “expedite” the ramping at large flows, a flow range can be set up where the spool can move
faster down to a flow range, where the slow down ramp is active. The overall goal with the parameter is
too optimize steering response time without degrading the anti-jerk performance. Set up fast ramp down
time Tfr before tuning this parameter. Setting YsetFr to 1000 eliminates the effect of the fast ramp down.
Typical settings are 500-800. Use trial and error.
Example:
A value of 800 can be interpreted as allowing the spool to ramp down with a fast ramp for flow requests
between maximum flow (1000) and 800/1000 of maximum flow.
Tfr This time defines the applied ramp time in the fast ramp-down range. It is defined as the ramp time
from maximum flow to no flow. This means that in practice, the actual fast ramp-down time is
proportional to the fast ramp-down range divided by 1000.
Use this optimization criterion: Ramp down as fast as possible for flow ranges, where jerks are not
significant. Typical values are 1-50 ms. The fast ramp down time shall always be less than the slow rampdown time. Once the value is set, it should not be adjusted anymore during further ramp parameter
optimization.
YAbortDownRamp To come around the problem of slow steering response for large down-ramp times,
especially if a sudden emergency change of direction is needed, a slow down-ramp can be aborted by
requesting a flow in the opposite direction. Once a slow down-ramp is aborted, an abort down-ramp
time, Tra is applied. Obviously Tra shall be significantly smaller than the slow down-ramp to get any
effect.
Tra is the ramp-down time applied when the slow down-ramp is aborted. This rampdown time shall
typically be much lower than the slow ramp-down time, Tfo, in order to gain any increased steering
responsiveness. Typical value is half the value of Tfo or Tfh time if vehicle speed dependency is applied
(Sr=2). Use trail and error.
Example:
A value equal to 500 means that the driver needs to steer out 500/1000 of maximum flow before the slow
down-ramp is aborted. 500 again corresponds to a certain steering wheel RPM.
Typical values are 100-300 to have the abort down ramp possibility and to avoid unintentional abort of
the down ramp due to steering wheel activation due to vibrations. Setting the value to 1000 disables the
abort down ramp functionality.
Symbol
Index
Default
Value range
Sr
4y17
0
Must be set at 2
Lr
4y19
0
0 to 10 (linear to max progressive)
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Steering by Low Priority Steering Device – Open Loop
Symbol
Index
Default
Value range
Lf
4y20
0
0 to 10
Tro
4y21
200
1 to 1000 ms
Tfo
4y23
350
1 to 1000 ms
Trh
4y22
200
1 to 1000
Tfh
4y24
350
1 to 1000
Verm
4y25
500
0 to 1000 (1 unit is 0.1 km/h)
YsetFr
4y32
1000
0 to 1000 (1 unit = 0.1% of max. flow).
Fast ramp-down is active in the port flow request range 1000 to YsetFr. The
default value disables fast ramp-down.
Tfr
4y33
100
1 to 1000 ms.
Tfr shall be smaller than Tfo and less than 150 ms.
YAbortDownRamp
4y34
0
0 to 500 (1 unit = 0.1% of max. flow).
The default value will force an down-ramp abort at a slight reverse port flow
request.
Typically YAbortDownRamp needs be increased to avoid unintentional
down-ramp aborts as this will infer a jerk on the driver.
Tra
4y35
1
1 to 1000 ms
Ramp-down time for canceled down-ramp
The discontinuities in the progressive characteristic are located at 50, 120 and 333 ([5.0;T at 25], [12,0;T at 50] and [33.3;T at 75] of max port flow
capacity)
Anti-jerk Ramp Parameter Tuning Guide
Tuning the parameters is an iterative process. The following sequence may be useful when tuning a
vehicle:
1. Initial setting: Set Tro to Tfr to Set YsetFr to 1000. Set Tra to Set YabortThreshold to 500.
2. Set the ramp-down time, Tfo, to a start value e.g. 500.
3. Decrease YsetFr from 1000 towards a smaller number. Observe which value of YsetFr where the level
of jerks starts to get worse to find the flow request range, where ramping has an effect. Optionally
increase Tfr to optimize on the fast ramp-down operation. Tfr should not exceed 150 ms and always
be smaller than Tfo.
4. Adjust the ramp-down time, Tfo, until at good anti-jerk performance is achieved.
5. Increase the ramp-up time, Tro, to further improve the anti-jerk performance. Tro is typically smaller
than Tfo.
6. Fine-tune the performance by experimenting with Tfr, Tra, and YsetFr. Note that the largest jerks shall
be tuned away with the ramp-up time, Tro, and ramp-down time, Tfo.
7. Finally the YAbortThrehold and Tra may be adjusted. Consider how many steering wheel RPM is
needed to abort the down-ramp. Secondly, adjust Tra to reduce the jerk when aborting the downramp. Obviously, Tra needs to be less than the down-ramp time, Tfo to get a faster steering response.
Typical values for Tra is 50 – 100 ms.
The above typical parameter settings may vary from vehicle to vehicle.
Soft (Cushion) End-stop
To prevent the steering actuator to hit the mechanical end lock with great speed, the PVED is able to slow
down the actuator speed when approaching the end lock electronically.
This functionality can be applied only in open-loop control mode, but requires that Steered wheel
feedback sensor is mapped and mounted on either the steered wheel or cylinder, to indicate the motionrange.
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PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Low Priority Steering Device – Open Loop
The red line in the figure below shows how the actuator is slowed down near the end lock position. The
black line in the figure below shows how port flow is reduced. The steering actuator signal must be
present in the PVED for this functionality to work.
Right end lock
1000
Cf
Yr, Software end lock position
500
Port flow
command
Steering actuator position
250
time
0
Off
Yact - steering actuator position
Q - port flow command
750
-250
Defaults
250 ms
Yl=-1000
-500
Yr=1000
-750
Cf=350
Off=50
-1000
Yl, Software end lock position
Left end lock
P005 221E
YR, YL The difference between the values of both parameter set the freedom of the steering actuator.
Normally, YR is set equal at the right mechanical end lock. YL is normally set equal to the left mechanical
end lock. For example, setting YR at 500 and YL at –500 reduces the freedom of the actuator by 50%. The
default values for YR and YL are set equal to position of the mechanically end locks.
Cf Sets the region where actuation speed is slowed down. This region starts from the position defined by
YR and YL. Making this region to small reduces or can eliminate the effect of soft stop.
The default value for Cf ensures the valve is closed proportionally with actuator position.
Off This parameter sets the permitted actuation speed when hitting the end lock defined by YR or YL.
When the steering actuator passed YR or YL, actuation speed will decay to zero.
The default sets a speed that allows building up pressure when the actuator is located at YR or YL.
Symbol
Index
Default
Value range
YR
4y07
1000
-1000 – 1000, Values smaller than 0 will be set equal to the positive equivalent
YL
4y08
-1000
-1000 – 1000, Values greater than 0 will be set equal to the negative equivalent
Off
4y28
50
0 to 1000 (0.0 - 100.0% of max port flow)
Cf
4y29
333
1 to 1000
See chapter Mapping steering signals, Steering actuator Sensor (feedback from vehicle wheels) and Steering actuator position to acquire “steering
actuator position”.
Tolsout Maximum time where the main spool is allowed to be operated proportionally within the valve
dead-bands. The main spool control range for this function can be seen on the Dead-band crossing on
page 26. This function is useful to eliminate frequent spool relocating events from its neutral to its deadband position and back (so called jumps) at small flow requests.
The flow request is 0 while moving the high priority steering device within the steering device deadband, db (see Set-point Transfer Function on page 87).
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Steering by Low Priority Steering Device – Open Loop
Spool Dead-band Hold Control Function
Dead-band Jump Control
Set Tolsout lower than 21 (ms) to momentarily set the main spool in neutral as soon as the flow request is
0, No proportional spool movement will take place. The spool will jump from neutral to either of the valve
dead-bands depending on a flow request. The steering device dead-band, db, has no impact for these
Tolsout values.
Dead-band Hold and Proportional Control
Setting Tolsout between 21 and 30000 (ms) defines the maximum time where the main spool is either set
on the valve dead-band or controlled proportionally within the valve dead-band (granted that the flow
request is 0 during this time).
After a flow request to either left or right port, the main spool will be set on the respective left or right
valve dead-band. Any steering device movement within the defined steering device dead-band, db, will
result in proportional main spool movement. Proportional control will be allowed for Tolsout ms.
If the flow request has been 0 for Tolsout ms, the main spool will be set in neutral and any steering device
movements within db will be ignored.
To utilize proportional control, a steering device dead-band, db, needs to be created. If db is set a low
value, the main spool will effectively be operated as dead-band jump control.
Responding to Flow Requests after Tolsout
If the main spool has been set in neutral after Tolsout ms, any flow request will cause the spool to
immediately jump to the relevant spool position with no initial proportional dead-band control.
Symbol
Index
Default
Value range
Tolsout
416
10 000
1 to 30 000 (ms)
Magnetic Valves OFF Control
Magnetic valves off delay time disables the magnetic valve bridge after a time specified in ms when the
flow request is 0, otherwise it remains enabled. This parameter is used when electrical energy
consumption by the magnetic valve bridge in the PVED must be reduced or to resolve a steering control
conflict between the OSP and the PVED-CL (implementing EHPS type 1 systems only).
The default value disables this functionality i.e. the magnetic valve bridge is enabled at all times. The
magnetic valve bridge is enabled when the PVED-CL receives a non-zero flow request.
Symbol
Index
Default
Value range
Magnetic valves Off delay time
415
30 000
1 to 30 000 (ms)
Resolving a Steering Control Conflict
On systems utilizing a PVED-CL, an EHPS valve, an OSP, a CAN or analogue steering device but no
steering wheel angle sensor (SASA) (EHPS type 1), the PVED-CL has no means to detect that the steering
wheel is being activated. A steering conflict between OSP steering and steering device steering is thus
possible. To resolve this conflict, set Tolsout to a value (typically 50 ms – 200 ms) to disable the magnetic
valve bridge when no flow request is being commanded with the steering device.
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Steering by Low Priority Steering Device – Closed Loop
Steering by High Priority Steering Device – Closed Loop
EHPS Type 2 Automatic Steering Diagram
Joystick or mini wheel
Low
priority
Steering angle sensor
OSP
OSP
Q
PVE EHPS
PVE
EHPS
Valve
valve
Q
Automatic steering
Steering
Steering
cylinder
cylinder
Position sensor
Vehicle speed
Functionality Tree
The tree below illustrates the functionality available in the PVED for steering by a potentiometer device
or by joystick or by mini wheel with speed output. The manufacturing default functionality is found by
following the red line. It can of course be modified by following the instructions in this chapter. The
switches in the tree are used to select the functionality required. In case different functionalities are
required, the EHPS software provides 5 programs from which the driver can select when the system is
fully operative.
For steering by a device without spring return the PVED provides closed loop position control. The
steering signal is monotonic and represents the angle of the physical device. These devices are normally
friction held to prevent unintentionally steering due to machine vibrations
Use this mode for implementation of proprietary auto-guidance applications i.e. auto-guidance
applications that do not conform to the ISO standardized auto-guidance messages (see Auto-steering on
page 105).
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Switches
Control principle switch
*
Cp
Ramp switch
Sensitivity switch
Channel mapping switch
Steering by Low Priority Steering Device – Closed Loop
Sse
Program number: Y
Open loop, fixed sensitivity, with fixed ramp
times
Open loop, fixed sensitivity, with ramp times
related to vehicle speed
Sr
Fixed Sr=1
Var Sr=2
Y=0
1
2
3
4
No Sr=0
Open loop, fixed sensitivity, with no
ramps applied
Fixed
Sse=1
Related to
position of
steering
actuator
Sse = 2
Open loop, sensitivity related to steering actuator
position, with fixed ramp times
Fixed Sr=1
Open loop, sensitivity related to steering actuator
position, with ramp times related to vehicle speed
Var Sr=2
No Sr=0
Related to
vehicle speed
Sse=3
Open loop
Cp=0
Fixed Sr=1
Open loop, sensitivity related to vehicle speed, with
fixed ramp times
Open loop, sensitivity related to vehicle speed, with
ramp times related to vehicle speed
Var Sr=2
No Sr=0
No signal (0)
AD1 (1)
AD2 (2)
CAN (4)
Open loop, sensitivity related to steering actuator
position, with no ramps applied
Open loop, sensitivity related to vehicle speed,
with no ramps applied
Closed loop
Cp=255
Closed loop, Fixed sensitivity, no ramps possible
default
* Sensitivity means: Port flow amplification
P005 089E
Tracking
For safety reasons, a tracking function ensures bump-less transition on control loop initialization. It forces
the user initially to operate the potentiometer knob into a position that matches zero deviation between
set point and current steering actuator position or by sweeping through it. While tracking, the
commanded port flow is limited at zero.
Yr, Yl, Lx, Xysat, db
10 ms
Xstl Potmeter
like
device
Angle
Qm
Kp
Setpoint
Port flow
limiter
Tracking
Q - Port flow
command
10 ms
Yact Actuator
position
P005 211E
Select the Control Principle
Cp selects the closed loop control using parameter index 4y02 equal to 255. Y selects the program and
ranges from 0 and 4. The value for y must be consistently used throughout the entire configuration of a
single program.
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Steering by Low Priority Steering Device – Closed Loop
Acquire the signals
See Mapping a Steering Device on page 34 on how to map an analogue or CAN-based high priority closedloop steering device and steering wheel angle sensor.
Create the Set Point
Steering actuator
position setpoint
Example:
db = 250, Lx = 10
Xysat = 750
YR = -750
YL = 500
1000
YL
750
500
250
Max input signal
for activating the
steering device
into the left
-1000
direction
-750
-500
-250
Defaults:
db = 0, Lx = 0
Xysat = 1000
YR = 1000
YL = -1000
saturation
-500
-750
Lx
YR
db
250
-250
Xysat
500
750
1 unit = 0.1% of
steering actuator at the
left end lock position
Right steering
actuator end-lock
1 unit = 0.1% of
steering actuator at the
right end lock position
A function provides 5 parameters to transform angle information to a steering actuator position set point.
-1000
Max input signal
for activating the
steering idevice
into the right
direction
1000
Xstl - Input signal: 1
unit = 0.1% of max
activation
Left steering
actuator end- lock
P005 212E
db Sets a dead band about the middle region of the signal. The parameters prevent self-steering, caused
by manufacturing deviations in the signal when the handle is in the middle or released position.
However, db is normally set to zero for pot-meter like steering devices.
The default value is set to serve pot-meter like steering devices
Lx Set the curve linearity. The parameter is set down when the cylinder position is too far (over-steer) for
small steering angles or vice versa. The optimum value for this parameter is closely related to:
•
•
•
•
The inherent linearity between steering actuator position and signal
The inherent linearity between device handle angle and signal
The inherent over or under-steer tendency of the vehicle when steering into curves
The default value will not effect the resulting relation.
YR, YL The difference between the values of both parameter set the freedom of the steering actuator.
Normally, YR is set equal at the right mechanical end lock. YL is normally set equal to the left mechanical
end lock. This results in steering to the right direction. In case an opposite steering behavior is required,
YR must be set at the negative equivalent and YL must be set at the positive equivalent (See example).
The default value for YR and YL is set equal to the mechanical locks of the steering actuator resulting in
the vehicle to steer in the right direction.
Yxsat Sets a threshold for the output to be at its maximum or minimum when the input signal exceeds
the threshold value. Yxsat is normally set down when more sensitivity is required than inherently
available with the steering device.
The default value will not effect the inherent sensitivity of the steering device.
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Steering by Low Priority Steering Device – Closed Loop
Symbol
Index
Default
Value range
db
4y05
0
0.0 to 250 (0.0 to 25.0% of max activation in the right steering direction)
Lx
4y06
0
-10 to 10 (-10 max regress, 0 linear, 10 max progress)
YR
4y07
1000
-1000 to 1000
YL
4y08
-1000
-1000 to 1000
Yxsat
4y03
1000
251 to 1000
Parameter Yxsat, db & Lx have same value in quadrant 2 & 3.
Lx in quadrant 1 or 4 is located at: [(Xysat+db)/2;YR*(20-Lx)/40].
Lx in quadrant 2 or 3 is located at: [-(Xysat+db)/2;YL*(20-Lx)/40].
Closing the Loop
Kp Amplifies the error between set point and current position. The optimum value for Kp is found when a
non-lagging, accurate, non-oscillating steering actuation without overshoot is achieved at extreme low
and high oil viscosities as specified in chapter: (robustness to changes sin dead times) and at low and
near max steering pressure when driving at low, high vehicle speed and reversed gear (robustness to
changes in damping & dead times). Moreover, Kp is closely related to valve capacity, stroke volume. See
section Steady State Error on page 61 for information on accuracy. The default value fits to steering
systems with a lock-to-lock time of 2 seconds at max port flow.
Qm Sets the maximum port flow. It effects the speed of the steering actuator to move towards the set
point position. Negative values of Qm are interpreted as the positive equivalent.
The default value is set equal to the inherent max port flow capacity of the valve and will therefore not
have any effect.
Symbol
Index
Default
Value range
Kp
408
50
0 to 200 (0.00 to 2.00% of port flow capacity of the valve for 0.1% positional
error)
Qm
4y27
1000
0 to 1000 (0.0 to 100.0 % port flow)
Eliminate Noise due to Frequent Pressure Build-up
Eliminating noise is accomplished by stopping the controller to respond to minor deviations between set
point and current actuator position. The spool inside the valve is set in neutral when the port flow
command has been within a threshold value (Qth) for a given time (Tclpout). The spool is reactivated
again when port flow command exceeds the threshold.
Tclpout Sets the time delay (ms) before the main spool is set in neutral.
Qth Sets the threshold value for port flow command when the controller is in steady state.
Symbol
Index
Default
Value range
Tclpout
417
3000
1 to 30000 (ms)
Qth
418
50
0 to 100 (0.0 to 10.0% of max port flow)
Magnetic Valves OFF Control
Magnetic valves off delay time Disables the magnetic valve bridge after a time specified in ms when the
flow request is 0, otherwise it remains enabled. This parameter is used when electrical energy
consumption by the magnetic valve bridge in the PVED must be reduced or to resolve a steering control
conflict between the OSP and the PVED-CL (implementing EHPS type 1 systems only).
The default value disables this functionality i.e. the magnetic valve bridge is enabled at all times. The
magnetic valve bridge is enabled when the PVED-CL receives a non-zero flow request
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Steering by Low Priority Steering Device – Closed Loop
Symbol
Index
Default
Value range
Magnetic Valves Off Delay Time
416
30 000
1 to 30 000 (ms)
Resolving a Steering Control Conflict
On systems utilizing a PVED-CL, an EHPS valve, an OSP, a CAN or analogue steering device but no
steering wheel angle sensor (SASA) (EHPS type 1), the PVED-CL has no means to detect that the steering
wheel is being activated. A steering conflict between OSP steering and steering device steering is thus
possible. To resolve this conflict, set Tolsout to a value (typically 50 ms – 200 ms) to disable the magnetic
valve bridge when no flow request is being commanded with the steering device.
Low Priority Steering Device Enable/Disable Control
The PVED functionality allows the user to dynamically enable or disable a steering device during
operation from the cabin MMI (via CAN bus). This functionality enables e.g. an armrest device to be
folded away for easy access to the cabin, while the system operational, to avoid the risk of unintended
device activation when the user enters or leaves the cabin.
Another user scenario is to disable one or more lower priority steering devices when only the steering
wheel device is in use for a longer period of time and the user wishes to eliminate the risk of
unintentional device activation.
System Requirements
The device enable/disable control functionality is only functional if the following conditions are fulfilled.
The system must be in operational state. The device that shall be enabled/disabled is mapped. An OSP for
hydraulic backup exists and the presence of the OSP is configured in the PVED.
Symbol
Index
Default
Value range
LowPrioritySteeringDeviceInterface
65103
0
0 (NONE), 1 (AD1), 2 (AD2), 4 (CAN)
OSP present
65109
0
0 (NONE), 255 (PRESENT)
If an OSP is not present, the device enable/disable control command is ignored. The OSP shall be present
because it is theoretically possible to electrically disable all steering devices if the primary steering wheel
sensor is not mapped. In this situation only the OSP pilot signals are driving the valve.
C
Caution
The vehicle system integrator shall consider the following to ensure a safe and reliable device enable/
disable functionality. The vehicle velocity shall be included in the decision whether a device disable
request shall be sent to the PVED or not. The location of the enable/disable button shall be wellconsidered to avoid unintentional enabling/disabling of a steering device. Unintended enabling/
disabling should be further avoided by requiring the enable/disable button to be pressed for a welldefined period of time. The OEM shall ensure that a steering device outputs a signal within a valid range
when the device is enabled.
Device Diagnostic Operation
The steering device diagnostic checks are performed both when the device is enabled and disabled.
Enable or Disable Joystick Steering Device
The device enable/disable control is executed by means of the DisableSteeringDevice command (see
PVED-CL Communication Protocol Technical Information, 11025584) from e.g. the man machine interface.
The DisableSteeringDevice command options are:
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Steering by Low Priority Steering Device – Closed Loop
•
•
•
Arm joystick enable/disable
Enable joystick
Disable joystick
Device enabled
armed
control byte = Arm device enable
control byte = Enable device
timeout or incorrect control byte
Device disabled
Device enabled
timeout or incorrect control byte
control byte = Disable device
Device disabled
armed
control byte = Arm device disable
Disabled at power-up = FALSE
Disabled at power-up = TRUE
The enabling or disabling of a steering device must follow the state transition sequence shown below in
order to minimize undesired enabling or disabling of a steering device.
The states, device enabled armed and device disabled armed are volatile states. A transition from these
states to the desired state requires reception of a command message within 200 ms after the reception of
first command message. Otherwise the device disable state will change back to its last state.
Boot-up State of Steering Device
The boot-up enable/disable state of the device can be configured with a parameter and can be changed
via the SetParameter command (see PVED-CL Communication Protocol Technical Information, 11025584).
Symbol
Index
Default
Value range
LpStdDisabledAtBootUp
64009
0
0 (FALSE), 255 (TRUE)
LpStd means Low Priority Steering Device.
If the device disable functionality is not desired, the parameter shall be 0.
Getting the Actual Enable/disable Status of the Device
The PVED will send one DisableSteeringDeviceResponse reply message to each DisableSteeringDevice
command it receives (or on time-out), containing the present enable/disable state for all steering devices.
This reply may be used by the MMI for acknowledge or display purposes (see PVED-CL Communication
Protocol Technical Information, 11025584).
The device enable/disable present status for all devices is also transmitted periodically in the
OperationStatus message which is transmitted on the CAN bus by default (see PVED-CL Communication
Protocol Technical Information, 11025584).
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Auto-steering
Auto-steering
EHPS Type 2 Automatic Steering System Diagram
Steering angle sensor
OSP
OSP
Q
Curvature command
PVE EHPS
PVE
Valve
EHPS
valve
Vehicle speed
Q
Steering
Steering
cylinder
cylinder
Position sensor
Guidance Commands
To facilitate the implementation of the PVED-CL for auto-steering or guidance, it is designed to use
ISO11783 auto-guide messages. This means the PVED-CL can easily be integrated with any GPS, rowguide, or similar controller sending ISOBUS specific curvature commands.
Calculating the Wheel Angle
The messages GuidanceSystemCommand and GuidanceMachineStatus are defined in the PVED-CL
Communication Protocol Technical Information, 11025584.
To position the wheels or the articulation angle correctly some vehicle geometry information is needed.
The parameter values are used by the control algorithm to calculating from Curvature into wheel setpoint (and from wheel set-point to Curvature for generating estimated curvature. The parameters and
shown in the parameter table below.
Other parameters mentioned in this chapter can be used with default values and should only be adjusted
if the performance needs fine-tuning.
Symbol
Index
Default
Value range
MaxWheelAngleLeft
65099
35 000
Maximum wheel angle to the left [mdeg].
Measured on the wheel where the wheel angle sensor is mounted.
MaxWheelAngleRight
65100
35 000
Maximum wheel angle to the right [mdeg].
Measured on the wheel where the wheel angle sensor is mounted.
VehicleLength
65112
4000
Wheelbase from front to rear axle in mm. Articulated vehicle: Distance from front
axle to joint.
ValveType
65121
1
1 means EHPS or PVB, 2 means EH.
SteeringType
65122
1
1 means front wheel steering, 2 means rear wheel steering, 3 means articulated
steering
VehicleLength2
(Only articulated)
65123
4000
Only used for articulated vehicles.
Length from joint to rear axle.
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Auto-steering
Closing the Loop
Sse, Sts0, Sts1,
Sts2, Sts3, Sts4,
Sts5, Vesm
20 ms
Port flow
limiter
Kp
Xext Set-point
Yact Actuator
position
Q - Port flow
command
20 ms
Ve Vehicle speed
P005 208E
The auto-steering functionality always uses closed loop control, hence the steered wheel or articulation
angle is read back to the PVED-CL, and used for control purposes to ensure correct positioning.
The functionality available in the PVED to steer by any curvature set-point controller is defined by
mapping the External Set-point Controller and a Steered Wheel Sensor according to Mapping a Steering
Device on page 34. As soon as these parameters are set, it is ready to run, but it is strongly recommended
to have a steering wheel sensor to disengage auto-steering just by turning the steering wheel.
Alternatively the power supply must be interrupted, or guidance message flagged as ‘Not intended for
steering’.
Trimming the System
To optimize the system functionality, ensure the parameters above were set correctly. If this was not
enough, try changing the parameters below.
Kp This parameter is closely related to valve capacity, stroke volume and amplifies the error between setpoint and current position. The optimum value for Kp is found when a non-lagging, accurate, nonoscillating steering actuation without overshoot is achieved at:
•
•
Extreme low and high oil viscosities as specified in Technical Data on page 24.
Low and near max steering pressure when driving at low, high vehicle speed and reversed gear
The default value fits to steering systems with a lock-to-lock time of 2 seconds at max port flow.
Qm Sets the maximum port flow. It effects the speed of the steering actuator to move towards the set
point position. Negative values of Qm are interpreted as the positive equivalent.
The default value is set equal to the inherent max port flow capacity of the valve and will therefore not
have any effect.
Ampl Factor that ‘amplifies’ the set-point. Used if the steered angle is always too small or too larger. It
applies to both sides, hence if the angle is too large left, and too small right, this factor cannot solve it –
that will probably be a steered wheel sensor calibration error.
ClosedLoopXspOffset Spool position offset which is added to spool position command to eliminate any
spool overlap. The offset ensures that the spool is always operated in a range where the valve outputs a
flow. This is especially important for auto-steering applications where any control error shall generate a
flow to correct the error.
Symbol
Index
Default
Value range
Kp
508
50
0 to 200
(0.00 to 2.00 % flow capacity of the valve for 0.1 % positional error)
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Auto-steering
Symbol
Index
Default
Value range
Qm
5y27
1000
0 to 1000 (0.0 to 100.0% of max port flow)
Ampl
5y37
1000
0 to 2000
(Factor 0.001; Setpoint from 0 to 2 times the setpoint message value)
ClosedLoopXspOffset
748
0
0 to 1000 (0 to ±7 mm)
Kp and ClosedLoopXspOffset correlates. By increasing ClosedLoopXspOffset, the proportional gain may
be reduced. It is recommended to first set ClosedLoopXspOffset to 20 and then tune Kp.
Noise due to Frequent Pressure Build-up
Eliminating noise is accomplished by stopping the controller to respond to minor deviations between set
point and current actuator position. The spool inside the valve is set in neutral when the port flow
command has been within a threshold value (Qth) for a given time (Tclpout). The spool is reactivated
again when port flow command exceeds the threshold value.
Tclpout Sets the time delay (ms) before the main spool is set in neutral.
Qth Sets the threshold value for port flow command when the controller is in steady state.
Symbol
Index
Default
Value range
Tclpout
517
3000
1 to 30000 (ms)
Qth
518
0
0 to 100 (0.0 to 10.0 % of max port flow)
Qth may introduce a control dead-band which may not be desired. Set Qth to 0 for tight closed-loop
control and for maximum precision.
Select a Fixed Sensitivity
A fixed steering sensitivity is chosen if the valve shall output a flow which is only dependent on the
control error and Kp.
Sse Selects between a fixed steering sensitivity, variable to steering actuator position or vehicle speed.
Set Sse to 1 to select the fixed sensitivity
Sts0 Sets a gradient between steering angle and requested port flow. Sts0 is normally set when max port
flow (defined by Qm) is achieved at maximum steering device input.
The default value is a gradient matching maximum requested port flow to maximum port flow at the
maximum steering angle.
Symbol
Index
Default
Value range
Sse
5y09
1
Must be set at 1
Sts0
5y10
1000
0 to 1000 (amplification of 0 to 100 %)
Default Sts0 shall be changed to 1000.
Vehicle Speed Dependent Sensitivity
Variable steering sensitivity related to vehicle speed is normally used to optimize directional stability
automatically and beyond the notice of the driver. The values and correlation is normally close related to
the present vehicle dynamics of the individual vehicle model. The Sts value is used to amplify the input
signal as described in Set-point Transfer Function on page 87 .
The correlation is defined by seven parameters. All Sts-parameters may be set equal to each other or set
monotonically falling for increasing vehicle speeds. The steering sensitivity between two table
coordinates is found by linear interpolation. The relation is equal for negative speeds.
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Auto-steering
max Sts = 1000
Steering sensitivity Sts
(Ve)
120
Sts0=105
100
Sts1=90
80
Vesm=500
Sts2=75
Sts3=60
60
Sts (Ve) saturates
Sts4=45
40
min Sts = 20
Sts5=30
0
100
200
300
400
500
600
700
800
900 1000
Ve - Vehicle speed: 1 unit = 0.1 km/h
Sse Selects between a fixed steering sensitivity, variable to steering actuator position or vehicle speed.
Set Sse to 3 to select the sensitivity related to vehicle speed.
Sts0 Sets the linear gradient between steering angle and requested port flow when the vehicle is
standing still. When the vehicle signal unintentionally not is mapped, Sts0 is applied constantly since
variable Ve remains 0.
In case the vehicle signal not is diagnosed, it is recommended to set Sts0 at a value where sufficient
directional stability at maximum vehicle speed is present.
Sts1 Sets the linear gradient between steering angle and requested port flow when the vehicle is driving
at 6.25% of the speed defined by parameter Vesm.
Sts2 Sets the linear gradient between steering angle and requested port flow when the vehicle is driving
at 12.50% of the speed defined by parameter Vesm.
Sts3 Sets the linear gradient between steering angle and requested port flow when the vehicle is driving
at 25 % of the speed defined by parameter Vesm.
Sts4 Sets the linear gradient between steering angle and requested port flow when the vehicle is driving
at 50 % of the speed defined by parameter Vesm.
Sts5 Sets the linear gradient between steering angle and requested port flow when the vehicle is driving
at 100 % of the speed defined by parameter Vesm.
Vesm Sets the region where steering sensitivity is variable to vehicle speed.
Symbol
Index
Default
Value range
Sse
5y09
1
Must be set at 3
Sts0
5y10
1000
20 to 1200 (Amplification of 0.2 to 12.00)
Sts1
5y11
20 to Sts0
Sts2
5y12
20 to Sts1
Sts3
5y13
20 to Sts2
Sts4
5y14
20 to Sts3
Sts5
5y15
Vesm
5y16
108
20 to Sts4
500
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Auto-steering
Symbol
Index
Default
Value range
Please note the parameter dependency of Sts.
See Mapping steering signals and J1939 Vehicle Speed to acquire “ Vehicle speed”
Magnetic Valves OFF Control
Magnetic valves off delay time Disables the magnetic valve bridge after a time specified in ms when the
flow request is 0, otherwise it remains enabled. This parameter is used when electrical energy
consumption by the magnetic valve bridge in the PVED must be reduced or to resolve a steering control
conflict between the OSP and the PVED-CL (implementing EHPS type 1 systems only).
The default value disables this functionality i.e. the magnetic valve bridge is enabled at all times. The
magnetic valve bridge is enabled when the PVED-CL receives a non-zero flow request.
Symbol
Index
Default
Value range
Magnetic valves Off delay time
515
30 000
1 to 30 000 (ms)
Resolving a Steering Control Conflict
On systems utilizing a PVED-CL, an EHPS valve, an OSP, a CAN or analogue steering device but no
steering wheel angle sensor (SASA) (EHPS type 1), the PVED-CL has no means to detect that the steering
wheel is being activated. A steering conflict between OSP steering and steering device steering is thus
possible. To resolve this conflict, set Tolsout to a value (typically 50 ms – 200 ms) to disable the magnetic
valve bridge when no flow request is being commanded with the steering device.
SASA disengage ability check
Disengaging auto-steering relies on the SASA sensor which transmits position changes when the steering
wheel is activated as described in Steering Device Transition, page 33. To address the risk that the SASA
steering wheel sensor should fail to deliver position changes (dx) to the PVED-CL – even if the steering
wheel is activated - and thus not be able to disengage auto-steering - a SASA disengage ability check can
be configured. The check is outlined below and will prevent auto-steering from being engaged if the
SASA sensor is failing:
StwDxActivationThreshold The SASA steering wheel position change threshold,|dx|, which shall be
exceeded before auto-steering can be engaged. The relation between dx and steering wheel rpm is: dx=
1 is equivalent to 1.4 rpm.
StwActivationTimeout The amount of time where immediate engaging auto-steering is kept possible
after |dx| getting lower than StwDxActivationThreshold. “Kept possible” in this context means: Without
first requiring detection of SASA steering wheel position changes.
Symbol
Index
Default
Value range
StwDxActivationThreshold
64022
5
0 to 4095
StwActivationTimeout
64023
0x7FFFFFFF
0 to 0x7FFFFFFF
Default is also denoted “disable value”.
Time in ms.
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Auto-steering
W Warning
It is recommended that the SASA disengage ability check is enabled in auto-steering applications to
reduce the risk of not being able to disengage auto-steering with the steering wheel (SASA). Note that
the check is not enabled by default.
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Reduced State
Reduced State
The PVED-CL contains functionality that allows the system architect to set up a “graceful degradation”
behavior if e.g. a sensor faults should occur. The overall objective is to sustain the machine up-time and
to allow the driver to finish the mission with as much steering performance as possible.
Faults on the following sensors can be configured to allow the PVED-CL to enter reduced state:
•
•
•
•
High Priority (HP) steering device faults
Low Priority (LP) steering device faults
Vehicle speed sensor faults
Steered wheel angle sensor faults
start
Is
fault related to
HP steering device OR
LP steering device OR
Vehicle speed sensor OR
Steered wheel angle sensor ?
Operation state
Fault detected
Reduced state
Yes
No
Yes
IS
SWAReducedModeAllowed OR
VSReducedModeAllowed OR
HPSTLReducedModeAllowed OR
LPSTLReducedModeAllowed
= TRUE ?
No
Fault state
Power off
Reduced Steering Functionality
The steering functionality in reduced state is dependent on which of the allowed faults are present as
presented below.
High Priority Steering Device Fault
HPSTDReducedModeAllowed parameter indicates to the PVED-CL error handler, that any fault related
to the High priority steering device shall bring the PVED-CL into reduced state and change the high
priority steering device functionality as follows:
•
•
High priority steering device disabled
High priority steering device enable not possible (see High Priority Steering Device Enable/Disable
Control on page 83)
Symbol
Index
Default
Value range
HPSTDReducedModeAllowed
64013
0
0 (FALSE), 255 (TRUE)
The parameter controls both analogue and CAN based steering devices.
‘False’ infers that the PVED-CL will enter fault state if a fault occurs.
The high priority steering device faults that can trigger reduced state can be found in J1939 Diagnostic
Interface on page 115.
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Reduced State
Low Priority Steering Device Fault
LPSTDReducedModeAllowed parameter indicates to the PVED-CL error handler, that any fault related
to the Low priority steering device shall bring the PVED-CL into reduced state and change the Low
priority steering device functionality as follows:
•
•
Low priority steering device disabled
Low priority steering device enable not possible (see Low Priority Steering Device Enable/Disable
Control on page 103)
Symbol
Index
Default
Value range
LPSTDReducedModeAllowed
64014
0
0 (FALSE), 255 (TRUE)
The parameter controls both analogue and CAN based steering devices.
‘False’ infers that the PVED-CL will enter fault state if a fault occurs.
The low priority steering device faults that can trigger reduced state can be found in J1939 Diagnostic
Interface on page 115.
Vehicle Speed Sensor Fault
The vehicle speed signal may be used by more steering devices. Any fault on the vehicle speed sensor or
signal will only affect the functionality that uses the speed signal. A steering device utilizing a speed
dependent functionality will continue to work while by-passing the vehicle speed dependent function.
VSReducedModeAllowed This parameter indicates to the PVED-CL error handler, that any fault related
to the CAN vehicle speed sensor shall bring the PVED-CL into reduced state and change steering
functionality as follows:
•
•
•
Speed dependent steering sensitivity is by-passed for all steering devices utilizing this functionality.
The PVED-CL will assume maximum speed in the absence of a valid vehicle speed signal. See Select a
Sensitivity with Relation to Vehicle speed on page 90.
Speed dependent ramp is by-passed for steering devices utilizing this functionality. The PVED-CL will
assume maximum speed in the absence of a valid vehicle speed signal. See Select Ramps with Ramp
Times Related to Vehicle Speed on page 50.
Program transition will ignore vehicle speed condition rule. See System State on page 20.
Symbol
Index
Default
Value range
VSReducedModeAllowed
64012
0
0 (FALSE), 255 (TRUE)
‘False’ infers that the PVED-CL will enter fault state if a fault occurs.
The vehicle speed sensor faults that can trigger reduced state can be found in Available J1939 Diagnostic
Trouble Codes, page 135.
Steered Wheel Angle Sensor Fails
The steered wheel angle sensor signal may be used by more steering devices. Any fault on the steered
wheel angle sensor or signal will only affect the functionality that uses the steered wheel angle signal. A
steering device utilizing this signal will continue to work while by-passing the functionality using the
steered wheel angle sensor signal.
SWAReducedModeAllowed parameter indicates to the PVED-CL error handler, that any fault related to
the steered wheel angle sensor shall bring the PVED-CL into reduced state and change steering
functionality as follows:
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Reduced State
•
•
•
Soft-stop functionality is by-passed
Actuator dependent steering sensitivity is by-passed.
Closed-loop control with any steering device or external set-point controller is not possible.
Symbol
Index
Default
Value range
SWAReducedModeAllowed
64011
0
0 (FALSE), 255 (TRUE)
‘False’ infers that the PVED-CL will enter fault state if a fault occurs.
The steered wheel angle sensor faults that can trigger reduced state can be found in J1939 Diagnostic
Interface on page 115.
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Diagnostic & Troubleshooting
Diagnostic
Any detected fault will bring the PVED-CL in reduced state or fail-safe state. Fail safe state infers that the
magnetic bridge is disabled and no pilot flow from the PVED-CL controls the valve. A fault that brings the
PVED-CL in fail-safe state is denoted a ‘critical’ fault. All critical faults are stored in the PVED-CL error
buffer for diagnostic purposes.
The PVED-CL may be accessed via CAN for diagnostic purposes while being in fail-safe state but
parameter configuration is not possible in fail-safe state. If the fault is related to the sensors or CAN bus
cable tree, these faults should be resolved and the PVED-CL should be powered up again. If the fault
requires parameters to be changed, the user must bring the PVED-CL in calibration mode (or operational
or reduced state if possible) before re-configuring the parameters.
Example on Resolving a Fault
A sensor is mapped (see Mapping a Steering Device on page 34) as present but does not exist in the
system. The sensor cannot be unmapped because the PVED-CL enters fail-safe state when powered on.
Solution
The PVED-CL needs to run in operational, reduced state or calibration state before any parameter may be
changed i.e. a) Simulate the sensor signal to satisfy the PVED-CL sensor checks while changing the
parameter or b) power up the PVED-CL in calibration mode.
Troubleshooting
The PVED-CL software performs diagnostic checks on the CAN bus interface, analogue sensors, magnetic
valve bridge interface, internal hardware peripherals and software execution plausibility. All detected
faults, which are rated as safety critical, will bring the PVED-CL in to its fail-safe state. Secondly the
diagnostic checks provide precise indication of the fault source and thus reduce system down-time.
However, not all unexpected system behavior can be traced via error codes. E.g. a too low gain-related
parameter value may result in too slow steering actuation but this cannot be detected as a fault. To rule
out faults resulting from conflicting system and parameter settings, the following trouble shooting steps
are recommended:
•
•
•
Check the list of typical faults first
Check the J1939 Diagnostic interface
Check the PVED-CL LED diagnostic interface (see LED Diagnostic on page 119)
Typical Fault Sources
The table below contains symptoms and possible resolutions. The PVED-CL operation status is the status
reflected in the CAN OperationStatus message (see PVED-CL Communication Protocol Technical
Information, 11025584), which is transmitted periodically on the CAN bus. If the PVED-CL operation
status is not available on the CAN bus, check the LED diagnostic interface see LED Diagnostic on page
119).
Symptom
PVED-CL
Operation Status
No actuation
Operational
(with high or low
priority steering
device or external setpoint controllers)
Fault
114
Cause/Solution
1. No or insufficient pressure is supplied to the valve.
2. No steering device is mapped.
3. Parameter Qm set to ~0
4. No or incorrect auto-steering message from external set-point controller
5. Spool sticks in neutral position
1. No or missing signal from steering signals at the AD1, AD2 or CAN interface.
2. Missing sensor signal (see J1939 Diagnostic Interface on page 115).
2. PVED-CL expects a different baud rate at network.
3. Insufficient electrical power supply to the PVED-CL.
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Diagnostic & Troubleshooting
Symptom
PVED-CL
Operation Status
Cause/Solution
4. PVED-CL has suffered a internal critical error.
No status available
1. CAN bus not operational. Check connection.
2. No electric power supply
3. PVED-CL is damaged. (see LED Diagnostic on page 119).
Opposite actuation
Operational
1. Hoses between valve and steering actuator are swapped.
2. Steering wheel angle sensor (and possibly OSP) is incorrectly installed.
3. Steering device input transfer function is mirrored.
4. The InvertInputSignal program parameter is set incorrectly (see page 127).
5. The ValveType parameter is set incorrectly (see page 124).
6. Steered wheel sensor outputs a constant valid voltage/value (closed loop).
Slow actuation
responds (delays)
Operational
1. Air is trapped in the steering actuator or hoses.
2. Oil has high viscosity. Make sure to apply to the technical requirements listed in Technical Data on
page 24.
3. The requested pressure is supplied with some delay (Pump).
Self-steering
Operational
1. The parameters Xspr_0 and Xspl_0 in the PVED-CL are not correctly set relative to the mechanical
dead-band location in the spool-opening characteristic. Read more information in Valve Interface on
page 25.
2. The actual neutral position and calibrated neutral position (steering devices such as joysticks, etc.) do
not match and causes a small output flow when the device is activated.
3. PVED-CL neutral spool position calibration is incorrect and needs re-adjusting (mechanical valve
defect).
4. Auto-steering is not disabled when a higher priority device is selected. Check if higher priority devices
are mapped.
5. Steering device dead-band is too small – noise may activate the device and cause the spool to jump
between left and right valve dead-band.
Actuation with low
gain
Operational
1. The amplification parameters (Sts) are set at a too low value (for steering devices) and too high for the
steering wheel sensor. Read more information on Select a fixed sensitivity.
2. The gain linearity index (Lx) is set at a high value.
3. Parameter “Vcap” is set greater than the true flow capacity of the valve.
4. Steering wheel angle sensor is installed upside down (causing a conflict with the OSP pilot signals).
5. The soft-stop functionality limits the flow because the steered wheel angle sensor input is not
correctly calibrated, mirrored or constant.
6. (Soft-stop). The steered wheels are being driven beyond the logical end-stop values (maximum output
flow in determined by the Off parameter.
7. The maximum flow parameter (Qm) is set too low for the particular program.
8. Then SASA sensor is not mapped as present – only the OSP is driving the valve.
9. The full range of a steering device relative to its calibration range is not being fully utilized.
10. If velocity dependent steering sensitivity is applied, the Sts settings may be incorrect or the vehicle
speed sensor outputs wrong data.
Fault
The hydraulic back-up system is active. The steering sensitivity is determined by the OSP.
J1939 Diagnostic Interface
There are two ways of accessing fault codes in the PVED-CL as outlined in a figure below.
•
•
Via J1939 diagnostic interface (SAE J1939-73)
Via J1939 proprietary protocol (PDU1 format)
11025583 • Rev CA • 11 Jan 2010
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Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Diagnostic & Troubleshooting
Accessing fault codes in the PVED-CL
The PVED operation status is the status reflected in the OperationStatus message (see PVED-CL
Communication Protocol Technical Information, 11025584) which is transmitted cyclically on the CAN
bus. If the PVED operation status is not available, check the LED diagnostic, LED Diagnostic on page 119.
Available J1939 Diagnostic Trouble Codes
SPN
Description
Lamp
Status
1083
AD1 short-circuit to GND
1083
CM
OC
Corresponding
PVED-CL Error Code
Red/Amber 4
0
Yes
10106
AD1 short-circuit to VCC
3
0
Yes
10108
1084
AD2 short-circuit to GND
4
0
Yes
10107
1084
AD2 short-circuit to VCC
3
0
Yes
10109
611
Missing sensor set-points
14
0
Yes
10210,
10212-10215,
10218-10221,
10223-10226,
10229-10231
612
Redundant wheel angle sensor values deviate too
much or CAN sensor set-point data out of range
14
0
Yes
10104, 10105, 10232,
10234-10238
613
Steering wheel speed plausibility check failure
Red
14
0
Yes
13063
84
Vehicle speed CAN sensor data plausibility check
failure
Red/Amber 12
0
Yes
10217
10228
627
Power supply voltage below min. threshold value
Red
4
0
Yes
13030
627
Power supply voltage exceeds max. threshold value
3
0
Yes
13031
1079
Sensor supply voltage below min. threshold value
4
0
Yes
13032
1079
Sensor supply voltage exceeds max. threshold value
3
0
Yes
13033
614
Loss of main spool control or spool position
plausibility check failure
14
0
Yes
13053, 13054
615 (1)
Vehicle speed CAN sensor data plausibility check
failure
Red/Amber 14
0
Yes
13064
615 (2)
Internal PVED-CL error (= any other classified as
critical)
Red
0
Yes
any other classified as critical
116
11025583 • Rev CA • 11 Jan 2010
FMI
14
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Diagnostic & Troubleshooting
1. This has been separated from the next row SPN 615 as this is the only case when the DTC with SPN
615 can signal the Lamp status set to Amber.
2. SPN 615 with the Lamp status set to Red indicates that other critical EHPS error has happened. The
user must retrieve an error code from the EHPS error buffer and use the table in section 2 to locate
the source of a problem.
The PVED-CL supports DM1, DM2 and DM3 according to SAE J1939-73 diagnostic protocol (see PVED-CL
Communication Protocol Technical Information, 11025584).
A sub-set of all possible PVED-CL fault codes are represented as standardized J1939-73 Suspect
Parameter Numbers (SPN). The sub-set is limited to interface-related faults, which are typically causing
most troubles.
AD1 and/or AD2 Short-circuit
Each of the two analog input ports are monitored for short-circuits to GND, VCC or positive battery
supply. The Failure Mode Identifier (FMI) differentiates between the two type of short-circuits. An internal
pull-down resistor on both analog input ports will pull the input level to GND if an analog input port is
left open. No analog input diagnostic is active if the analog input is not mapped.
Missing CAN Sensor Set-points
SPN 611 indicates a fault due to invalid timing or missing input signals from the sensors, most likely due
to a failing CAN sensor or cable tree fault. In this context, input signals are both CAN messages and
analog samples from sensors. However, missing analog samples or invalid timing of analog samples can
only be caused by an internal PVED-CL fault – nothing can be concluded about the analog sensors from
this SPN.
Invalid timing means that the requirements to the period that data has to be received within, has not
been met. This could again be caused by an incorrectly configured CAN sensor or a heavy CAN bus-load,
restricting the CAN sensor messages to be transmitted at their expected time.
SPN
PVED-CL
Error Code
Possible root cause
611
10210
SASA steering wheel sensor message period exceeds 100 ms
10212
High Prio. steering device CAN sensor message period exceeds 100 ms
10213
Low Prio. steering device CAN sensor message period exceeds 100 ms
10214
Primary wheel angle CAN sensor message period exceeds 100 ms
10215
Redundant wheel angle CAN sensor message period exceeds 100 ms
10218
Analog input 1 sample period exceeds 5 ms. Internal PVED-CL fault
10219
Analog input 2 sample period exceeds 5 ms. Internal PVED-CL fault
10220
Analog spool position input sample period exceeds 5 ms. Internal PVED-CL fault
10221
SASA steering wheel sensor messages are missing
10223
High priority steering device CAN sensor messages are missing
10224
Low priority steering device CAN sensor messages are missing
10225
Primary wheel angle CAN sensor messages are missing
10226
Redundant wheel angle CAN sensor messages are missing
10229
Analog input 1 samples are missing. Internal PVED-CL fault
10230
Analog input 2 samples are missing. Internal PVED-CL fault
10231
Analog spool position input samples are missing. Internal PVED-CL fault
11025583 • Rev CA • 11 Jan 2010
117
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Diagnostic & Troubleshooting
Redundant Wheel Angle Sensor Values Deviate too much or CAN Sensor Set-point Data out of Range
SPN 612 indicates more faults, depending on the actual system configuration i.e. many of the PVED-CL
error codes can be ignored by using the knowledge of the actual sensor mapping.
SPN
PVED-CL
Error Code
Possible root cause
612
10104
The primary steered wheel angle sensor set-point and the redundant steered wheel angle sensor set-point deviates too
much. One of the sensors may not work or the sensor values differs due to a physical sensor offset
10105
The deviation between the primary steered wheel angle sensor set-point and the redundant steered wheel angle sensor
set-point exceeds the valid range.
10232
The SASA steering wheel sensor set-point exceeds the valid range.
10234
High priority steering device CAN sensor set-point exceeds the valid range.
10235
Low priority steering device CAN sensor exceeds the valid range.
10236
Primary wheel angle CAN sensor set-point exceeds the valid range.
10237
Redundant wheel angle CAN sensor set-point exceeds the valid range.
10238
External CAN set-point generator curvature or spool position set-point exceeds the valid range.
Steering Wheel Speed Plausibility Check Failure
SPN 613 indicates an abnormal steering wheel activation i.e. the measured rpm exceeds 600 rpm.
Vehicle Speed CAN Sensor Data Plausibility Check Failure
SPN 84 indicates that the vehicle speed sensor data is invalid.
SPN
PVED-CL
Error Code
Possible root cause
84
10217
Vehicle speed CAN sensor message period exceeds 150 ms.
10228
Vehicle speed CAN sensor messages are missing.
Power Supply Voltage
SPN 627 indicates that the battery voltage supply is either below 9V or has exceeded 32V.
Sensor Supply Voltage
SPN 1079 indicated that the regulated 5V supply for external sensors is out of range. This could be due to
a short-circuit, overload or an internal PVED-CL hardware fault
Loss of Main Spool Control or Spool Position Plausibility Check Failure
SPN 614 indicates that the main valve spool is out of control. This may be caused by an incorrect sensor
mapping i.e. if a SASA sensor is not mapped as present and the steering wheel is activated
simultaneously with e.g. a joystick. Secondly it may indicate that the spool position signal is out of range.
Subsequently the fault my also be traced to a PVED-CL hardware error.
SPN
PVED-CL
Error Code
Possible root cause
614
13053
Main valve spool is out of control.
13054
Main valve spool position signal is out of range.
118
11025583 • Rev CA • 11 Jan 2010
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Diagnostic & Troubleshooting
Internal PVED-CL Error
SPN 615 indicates that a critical PVED-CL fault has happened. The user must look up the EHPS error
buffer to retrieve the EHPS error code and apply the table with PVED-CL error codes to locate the error
source. The user shall locate the last entered error entry which is either the last error code before the ‘No
error’ code or the error code at the last error entry. If the error buffer is filled up, new error codes will
overwrite the error code in the last error entry.
LED Diagnostic
The PVED-CL has a LED mounted at the connector side for low level diagnostic.
LED color
PVED-CL Operation
Status
PVED-CL Status
Black / Off
Not available
No battery power is supplied to the PVED-CL
Orange
Fault
PVED-CL is in fault state. More information is available in DM1 CAN message.
Operational
PVED-CL is operational but no device has been selected.
Once a steering device is activated, the LED changes to green.
Operational
PVED-CL is operational
Reduced
PVED-CL is in reduced state
Calibration
PVED-CL is operating in calibration mode
Not available
A critical PVED-CL specific fault has happened – PVED-CL is in fail silent state (silent ~ disconnected from
the CAN bus)
Green
Red
11025583 • Rev CA • 11 Jan 2010
119
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Appendix
System Parameters
Inde Name
x
Description
Data Range
Type
Defau Lo
lt
ck
ed
702
Lspl
Index for controlling linearity of left flow characteristic
S16
[-10 ; 10]
0
703
Lspr
Index for controlling linearity of right flow
characteristic
[-10 ; 10]
0
706
Vcap
Valve capacity [l/min]
[5; 120]
25
707
StrkVol
Stroke Volume [cm3]
[100 ; 8000]
600
725
RiOSP
Backlash of OSP
[0; 160]
50
726
Sts_backup
Steering sensitivity of back up system
[300; 700]
500
729
Xspl_1000
Max spool position at left side of neutral
[-1000; -300] EH/OSPE
[-1000; -400] EHPS
-1000
✓
✓
737
Xspl_0
Spool position at left spool dead band
[-250; 0] EH/OSPE
[-350; 0] EHPS
-185
✓
✓
738
Xspr_0
Spool position at right spool dead band
[-250; 0] EH/OSPE
[-350; 0] EHPS
185
✓
✓
747
Xspr_1000
Max Spool position at right side of neutral
[300; 1000] EH/OSPE
[400; 1000] EHPS
25
✓
✓
748
ClosedLoopXspOffset
Auto-calibration set-point offset
[0; 300]
25
✓
✓
750
Ktol
Tolerance parameter for plausibility check and
steering actuator dynamics
U16
[500; 1000]
800
758
XspCalibrationOffSet
Auto-calibration set-point offset
S16
[0; 300]
25
✓
✓
798
Ve_100_to_0_time
Fastest time in ms to deceleration from 100 to 0 km/h
U16
[0; 32000]
0
799
Ve_0_to_100_time
Fastest time in ms to acceleration from 0 to 100 km/h
832
SensorSupplyVoltage
Sensor supply voltage [mV]. Read only.
[0; 5100]
833
Temperature
Temperature measured on the PVED-CL printed circuit S16
board in degrees C. Read only.
[-50; 451]
931
OperationTime
The time PVED has been operating since the first boot. U32
Unit: 6 min. Read-only.
[0 ; 4294967295]
932
Temperature histogram interval 1
[0 ; 4294967295]
933
Temperature histogram interval 2
934
Temperature histogram interval 3
935
Temperature histogram interval 4
936
Temperature histogram interval 5
937
Temperature histogram interval 6
938
Temperature histogram interval 7
939
Temperature histogram interval 8
940
Temperature histogram interval 9
941
Temperature histogram interval 10
942
Temperature histogram interval 11
943
Temperature histogram interval 12
944
Temperature histogram interval 13
945
Temperature histogram interval 14
946
Temperature histogram interval 15
Number of 6. minute ticks where the PVED-CL is
operating in temperature interval :
1 : < -40 deg. C
2 : [-40; -31] deg. C
3 : [-30; -21] deg. C
4 : [-20; -11] deg. C
5 : [-10; -9] deg. C
6 : [ 0; 9] deg. C
7 : [ 10; 19] deg. C
8 : [ 20; 29] deg. C
9 : [ 30; 39] deg. C
10: [ 40; 49] deg. C
11: [ 50; 59] deg. C
12: [ 60; 69] deg. C
13: [ 70; 79] deg. C
14: [ 80; 89] deg. C
15: [ 90; 99] deg. C
16: [100; 109] deg. C
17: [110; 119] deg. C
18: [120; 129] deg. C
19: [130; 139] deg. C
120
11025583 • Rev CA • 11 Jan 2010
U16
S16
U32
Not
Res
tore
d
✓
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Appendix
Inde Name
x
Description
947
Temperature histogram interval 16
948
Temperature histogram interval 17
20: > 140 deg. C
The temperature measured on the PVED-CL printed
circuit as long as the PVED-CL is powered. Read only
949
Temperature histogram interval 18
950
Temperature histogram interval 19
951
Temperature histogram interval 20
Data Range
Type
Defau Lo
lt
ck
ed
Not
Res
tore
d
✓
6300 - not used 0
20 general purpose storage
parameters
6301
9
- user defined -
U32
[0 ; 4294967295]
0
6400 StatusReportsPGNBase
2
Offset for proprietary B messages that contains status
data
U8
[0; 253]
0
6400 PvedSourceAddress
3
PVED-CL Source Address
19
6400 VehicleSpeedSensorSourceAddress
4
Source Address of the vehicle speed sensor
251
6400 ControlDeviceSourceAddress
5
Source Address of the MMI controller.
252
6400 ConfigurationDeviceSourceAddress
6
Source Address of the configuration/diagnostic tool.
253
6400 HPExtSourceAddress
7
Source Address of the high priority external set-point
generator
28
6400 HPStdDisabledAtBootUp
8
High priority steering device state at power-up
(device enable/disable)
6400 LPStdDisabledAtBootUp
9
Low priority steering device state at power-up
(device enable/disable)
6401 HPExtDisabledAtBootUp
0
High priority external set-point controller state
at power-up (enable/disable)
6401 WAReducedModeAllowed
1
Reduced mode switch for the wheel angle sensor
signal
6401 VSReducedModeAllowed
2
Reduced mode switch for the vehicle speed sensor
signal
6401 HPStdReducedModeAllowed
3
Reduced mode switch for the high priority steering
device
6401 LPStdlReducedModeAllowed
4
Reduced mode switch for the low priority steering
device.
6401 HPStwPowerUpTimeout
5
Power-up timeout value for the steering wheel signal
Unit: 1 ms.
6401 HPStdPowerUpTimeout
6
Power-up timeout value for the high priority steering
device set-points (CAN) Unit: 1 ms.
6401 LPStdPowerUpTimeout
7
Power-up timeout value for the low priority steering
device set-points (CAN) Unit: 1 ms.
6401 WAPowerUpTimeout
8
Power-up timeout value for the wheel angle sensor
Unit: 1 ms.
6401 VSPowerUpTimeout
9
Power-up timeout value for the vehicle speed signal
Unit: 1 ms.
11025583 • Rev CA • 11 Jan 2010
BOO
L
Enabled: 0
Disabled: 255
0
Not allowed: 0
Allowed: 255
0
U16
[100; 10 000]
100
U16
[60; 10 000]
60
[160; 10 000]
160
121
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Appendix
Inde Name
x
Description
Data Range
Type
6402 StwDxFilterThreshold
0
Threshold for the steering wheel dx filter
6402 StwDxFilterStartTime
1
Timeout-value for the steering wheel dx filter
activation
Unit: 1ms
U16
6402 StwDxActivationThreshold
2
The SASA steering wheel position change threshold,|
dx|, which shall be exceeded before auto-steering can
be engaged. The relation between dx and steering
wheel rpm is: dx= 1 is equivalent to 1.4 rpm.
U16
[0 ; 4095]
5
6402 StwActivationTimeout
3
The amount of time where immediate engaging autosteering is kept possible after |dx| getting lower than
StwDxActivationThreshold. “Kept possible” in this
context means: Without first requiring detection of
SASA steering wheel position changes.
U32
[0 ; 2147483647]
21474
83647
6500 SD_ID
0
Danfoss ID according to J1939 / ISO11783
U8
[0 ; 253]
57
✓
✓
6500 PVEDSerialNo
1
PVED barcode number
U32
[0 ; 4294967295]
0
✓
✓
6500 SalesOrderNo
2
Danfoss Sales Order Number. Identifies hardware
configuration, software version and parameter setup.
✓
✓
6500 SWVersionNo
3
Installed software version. Read only.
✓
✓
6500 ParamDefFile
4
Identifies the parameter set file applied at production
time.
U16
✓
✓
6500 - not used –
5
- user defined –
U32
6500 - not used –
6
- user defined –
6505 BaudRate
1
The CAN bus physical baud rate
6505 AD1_500_Left
5
Value of the analogue AD 1 between extreme left and
neutral
6506 AD1_500_Right
2
0,1: Disable filter
Defau Lo
lt
ck
ed
Not
Res
tore
d
2
[2 ; 4095]
0: filter always enabled 0
[1 ; 65515]
> 65515: Disable filter
0
250
✓
300
✓
Value of the analogue AD 1 between extreme right
and neutral
700
✓
6506 AD2_500_Left
9
Value of the analogue AD 2 between extreme left and
neutral
300
✓
6507 AD2_500_Right
6
Value of the analogue AD 2 between extreme right
and neutral
700
✓
6508 AD1_1000_Left
0
Extreme value of the analogue input AD 1 steering left
{125, 250, 500}
100
✓
6508 AD1_1000_Right
3
Extreme value of the analogue input AD 1 steering
right
[30 ; 957]
900
✓
6508 AD1_Neutral
6
Neutral value of analogue input AD 1
500
✓
6508 AD_1_Linear
7
Defines whether AD1 scaling is based on 3 or 5 points
255
✓
122
11025583 • Rev CA • 11 Jan 2010
U16
BOO
L
[30 ; 957]
5-point: 0
3-point: 255
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Appendix
Inde Name
x
Description
Data Range
Type
Defau Lo
lt
ck
ed
Not
Res
tore
d
6508 AD2_1000_Left
9
Extreme value of the analogue input AD 2 steering left U16
100
✓
6509 AD2_1000_Right
2
Extreme value of the analogue input AD 2 steering
right
300
✓
6509 AD2_Neutral
5
Neutral value of analogue input AD 2
500
✓
6509 AD_2_Linear
6
Defines whether AD2 scaling is based on 3 or 5 points
BOO
L
5-point: 0
3-point: 255
255
✓
6509 AnalogChannelCompensation
8
Analogue input voltage compensation
Enables radiometric measurement of voltages which
are proportional to the PVED-CL 5V external reference
voltage (such as simple resistive potentiometers).
U16
No compensation (0)
0
✓
W
Warning
Do not use for sensors which outputs are already
compensated.
6509 MaxWheelAngleLeft
9
Maximum wheel angle to the left [mdeg]. Measured
on
the wheel where the wheel angle sensor is mounted
6510 MaxWheelAngleRight
0
Maximum wheel angle to the right [mdeg]. Measured
on
the wheel where the wheel angle sensor is mounted
6510 SteeringWheelSensorPresent
1
Steering wheel sensor configuration (SASA Sensor)
[30 ; 957]
Compensation on AD1
(1)
✓
Compensation on AD2
(2)
✓
Compensation on
AD1+AD2 (3)
✓
U32
[0 ; 50000]
35000
BOO
L
Not present: 0 Present: 0
255
Index
Name
Description
Data
Type
Range
De
fau
lt
65102
HighPrioritySteeringDeviceInterface
High priority steering device configuration
(joystick, potentiometer, other)
U8
No device connected (0)
0
Analogue device on AD1 (1)
Analogue device on AD2 (2)
CAN-based device (4)
65103
LowPrioritySteeringDeviceInterface
Low priority steering device configuration
(joystick, potentiometer, other)
No device connected (0)
Analogue device on AD1 (1)
Analogue device on AD2 (2)
CAN-based device (4)
65104
PrimaryWheelAngleSensorInterface
Steered wheel angle sensor configuration
(feedback from steered wheels)
No device connected (0)
Analogue device on AD1 (1)
Analogue device on AD2 (2)
CAN-based device (4)
65105
ExternalSetPointControllerPresent
External set-point controller configuration (GPS)
65107
RedundantWheelAngleSensorPresent
Redundant steered wheel angle sensor configuration
65108
VehicleSpeedSensorPresent
Vehicle Speed J1939 signal IO configuration
65109
OSPPresent
Defines whether the hydraulic backup is present.
Only on EHPS system.
11025583 • Rev CA • 11 Jan 2010
BOOL Not present: 0
Present: 255
123
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Appendix
Index
Name
Description
Data
Type
Range
De
fau
lt
65110
SpoolMonitorPresent
Valve main spool monitoring.
Monitors if main spool set-point and actual spool
position relationship.
65112
VehicleLength
Distance [mm] between the front and rear axles.
Articulated vehicles: distance [mm] between the front
axle and the articulation point.
U16
[1 ; 65535]
40
00
65113
VehicleType
Defines the vehicle type
[0 ; 65535]
0
65114
AntennaOffsetX
Offset or distance of Antenna related to reference point,
in X direction [mm]
65115
AntennaOffsetY
Offset or distance of Antenna related to reference point,
in Y direction [mm]
65116
AntennaOffsetZ
Offset or distance of Antenna related to reference point,
in Z direction [mm]
65117
DMUOffsetX
Offset or distance of DMU related to reference point, in
X direction [mm]
65118
DMUOffsetY
Offset or distance of DMU related to reference point, in
Y direction [mm]
65119
DMUOffsetZ
Offset or distance of DMU related to reference point, in
Z direction [mm]
65120
OSPSize
65121
ValveType
Size of hydraulic steering unit in cm3
[20 ; 1200]
20
Defines type of the valve PVED-CL is mounted on
EHPS: 1, EH: 2
1
65122
SteeringType
Used for Auto-steering algorithm selection
Front wheel steering (1)
Rear wheel steering (2)
Articulated steering (3)
65123
VehicleLength2
Articulated vehicles: distance [mm] between the rear
axle and the articulation point
[1 ; 65535]
40
00
65124
STWSensorTransmissionRate
Steering wheel sensor transmission rate
5 ms (0)
1
10 ms (1)
15 ms (2)
Program Parameters
Name
Data Description of parameter
type
Steering Steering device
wheel
High
Low
Priority Priority
External
set-point
controller
Range
Default
Pid
S16
Program identification number
1y00
3y00
4y00
5y00
[0; 34]
{0, 20, 25, 30}
Did
U8
Device identification number
1y01
3y01
4y01
5y01
[0; 4]
{0, 2, 3, 4}
Cp
BOOL Control principle
1y02
3y02
4y02
5y02
Open loop: 0
Closed loop: 255
{0, 0, 0, 255}
Xysat
S16
Saturation of Y at input X
1y03
3y03
4y03
5y03
[0; 1000]
1000
Ri
Steering wheel backlash
1y04
3y04
4y04
5y04
[0; 200]
0
db
Dead band
1y05
3y05
4y05
5y05
[0; 250]
{5, 0, 0, 0,}
Lx
Linearity index
1y06
3y06
4y06
5y06
[-10 ; 10]
0
YR
Right position limit
1y07
3y07
4y07
5y07
[0; 1000]
1000
124
11025583 • Rev CA • 11 Jan 2010
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Appendix
Name
Data Description of parameter
type
Steering Steering device
wheel
High
Low
Priority Priority
External
set-point
controller
Range
Default
-1000
YL
Left position limit
1y08
3y08
4y08
5y08
[-1000 ; 0]
Sts0
Steering sensitivity at 0 % of Vesm
1y10
3y10
4y10
5y10
Sts1
Steering sensitivity at 6 % of Vesm
1y11
3y11
4y11
5y11
Sts2
Steering sensitivity at 12 % of Vesm
1y12
3y12
4y12
5y12
[20; 1200]
{400, 105, 105, 1000}
External set-point
{400, 90, 90, 1000}
generator
{400, 75, 75, 1000}
[0; 1000]
Sts3
Steering sensitivity at 25 % of Vesm
1y13
3y13
4y13
5y13
{400, 60, 60, 1000}
Sts4
Steering sensitivity at 50 % of Vesm
1y14
3y14
4y14
5y14
{400, 45, 45, 1000}
Sts5
Steering sensitivity at 100 % of Vesm
1y15
3y15
4y15
5y15
Lr
Ramp-up linearity index
1y19
3y19
4y19
5y19
Lf
Ramp-down linearity Index
1y20
3y20
4y20
5y20
Tro
Ramp-up time at vehicle speed = 0
1y21
3y21
4y21
5y21
Trh
Ramp-up time at vehicle speed = Verm
1y22
3y22
4y22
5y22
Tfo
Ramp-down time at vehicle speed = 0
1y23
3y23
4y23
5y23
Tfh
Ramp-down time at vehicle speed = Verm
1y24
3y24
4y24
5y24
Qm
Maximum port flow
1y27
3y27
4y27
5y27
1000
Off
Maximum port flow at end-stop
(Soft end-stop)
1y28
3y28
4y28
5y28
50
Cf
Active soft end-stop port flow range
1y29
3y29
4y29
5y29
[1; 1000]
333
kc
Minimum & maximum steering sensitivity
bound in % of Sts(k)
(Steering wheel drift control)
1y30
3y30
4y30
5y30
[0; 20]
20
kd
Proportional gain for steering wheel drift
control
1y31
3y31
4y31
5y31
[0; 200]
0
Fast ramp-down range (rate limitation)
1y32
3y32
4y32
5y32
[0; 1000]
1000
Tfr
Fast ramp-down time (rate limitation)
1y33
3y33
4y33
5y33
[1; 1000]
100
YAbort
Down
Ramp
Input flow command threshold for canceling 1y34
down-ramp (rate limitation)
3y34
4y34
5y34
[0; 500]
0
Tra
Ramp-down time for canceled down-ramp
1y35
3y35
4y35
5y35
[1; 1000]
1
Set-point amplification [Factor 0.001]
YsetFr
Ampl
S16
U16
{400, 30, 30, 1000}
[0; 10]
0
[1; 1000]
1
350
1y36
3y36
4y36
5y36
[0; 2000]
1000
InvertI BOOL Steering device signal inversion control
nputSi
gnal
1y37
3y37
4y37
5y37
Normal: 0
Inverted: 255
0
Sse
Steering sensitivity selector
1y09
3y09
4y09
5y09
Fixed 1
Actuator position
dependent 2
Vehicle speed
dependent 3
1
Sr
Rate limitation selector (anti-jerk)
1y17
3y17
4y17
5y17
No ramps applied 0
0
Fixed ramp times
1
Vehicle speed
dependent 2
Vesm
Vehicle speed range where steering
sensitivity is dependent on vehicle speed.
1y16
3y16
4y16
5y16
[1; 1000]
S16
11025583 • Rev CA • 11 Jan 2010
{50, 50, 50, 50}
125
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Appendix
Name
Data Description of parameter
type
Steering Steering device
wheel
High
Low
Priority Priority
External
set-point
controller
Range
Default
1y25
5y25
[0; 1000]
500
Vehicle speeds higher than Vesm will
saturate steering sensitivity at Sts5.
Verm
Vehicle speed range where ramp up/down
time is dependent on vehicle speed.
Vesm [vehicle speed • 10]
Vehicle speeds higher than Verm will
saturate ramp times at Trh and Tfh
respectively.
3y25
4y25
Steering Device Parameters
Name
Data type
Description of parameter
Steeri Steering
ng
device
wheel
High
Low
Priorit Priorit
y
y
Extern Range
al setpoint
contro
ller
Default
Kp
SIGNED16
Proportional gain for closed loop
108
308
408
508
[0; 200]
50
Full_Strk
SIGNED16
Fastest steering device input - minimum to
maximum or vice versa (ms).
For steering wheel device it is the time for one
revolution.
111
311
411
511
[1; 2000]
{500,
200,
200,
200}
Magnetic Valves Off
Delay Time
SIGNED16
Delay from main spool position in neutral position to 115
valve controller is disabled (ms).
A delay equal to default keeps the valve controller
constantly enabled.
315
415
515
[1; 30000]
30 000
TolsOut
SIGNED16
Time out value for main spool position variable at
dead band in open loop control (ms)
116
316
416
516
[1; 30000]
10 000
TclpOut
SIGNED16
Time out value for main spool position variable
between Valve opening threshold and dead band in
closed loop control [ms]
117
317
417
517
[1; 30000]
3000
Qth
SIGNED16
Valve Opening Threshold for main spool position
control in closed loop.
118
318
418
518
[0; 100]
{50, 50,
50, 0}
Steering Motion
Threshold
SIGNED16
Active State speed threshold.
Detection of steering request with a steering device
(% • 10 of maximum activation speed)
119
319
419
519
[0; 2000]
{50, 100,
100,
100}
P_Ve_Transit_Threshold
SIGNED16
Vehicle speed Threshold value to allow new
programs to be used for steering. (km/h • 10)
127
327
427
527
[0; 1000]
50
126
11025583 • Rev CA • 11 Jan 2010
Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
11025583 • Rev CA • 11 Jan 2010
127
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