Green Maraiya

Green Maraiya
SOME STUDIES ON CONTROL OF A DC-SERVO MOTOR
Green Maraiya
Department of Electrical Engineering
National Institute of Technology, Rourkela
2012-2014
SOME STUDIES ON CONTROL OF A DC-SERVO MOTOR
A thesis submitted in partial fulfillment of the
Requirements for the degree of
Master of Technology
In
Electrical Engineering
By
GREEN MARAIYA
(212EE3234)
UNDER THE SUPERVISION OF
PROF.SANDIP GHOSH
Department of Electrical Engineering
National Institute of Technology, Rourkela
2012-2014
Department of Electrical Engineering
National Institute of Technology, Rourkela
CERTIFICATE
This is to confirm that the thesis entitled, "SOME STUDIES ON CONTROL OF DC-SERVO
MOTOR" put together by Mr. GREEN MARAIYA in halfway satisfaction of the prerequisites
for the recompense of Master of Technology Degree in ELECTRICAL ENGINEERING with
specialization in "CONTROL & AUTOMATION" at the National Institute of Technology,
Rourkela is a genuine work did by him under my supervision and direction.
To the least complex of my data, the matter exemplified inside the theory has not been submitted
to the next University/ Institute for the grant of any Degree or endorsement
Date:
Place: Rourkela
PROF.SANDIP GHOSH
Electrical Department
National Institute Technology
Rourkela-769008
ACKNOWLEDGEMENTS
This project is without a doubt the most critical achievement in my life and it would be
unimaginable without individuals who backed me and had confidence in me.
I might want to augment my appreciation and my genuine on account of my noteworthy,
regarded Prof.Sandip Ghosh. He is an incredible instructor with profound vision as well as
above all a kind individual. I genuinely thank for his excellent direction and support. His trust
and backing enlivened me in the most critical minutes of settling on right choices and I am happy
to work under his supervision.
I might want to thank all my companions and particularly my comrades for all the mindful and
brain animating exchanges we had, which provoked us to think past the self-evident. I have
appreciated their brotherhood such a great amount of throughout my stay at NIT, Rourkela.
To wrap things up I might want to thank my guardians, who taught me the quality of diligent
work by their case. They rendered me huge help being separated throughout the entire residency
of my stay in NIT Rourkela.
Green Maraiya
National Institute of Technology
Rourkela-769008
CONTENTS
List of Figure……………………………………………………………………………………..i
List of Table……………………………………………………………………………………...iii
Abstract…………………………………………………………………………………………...iv
Chapter1 Control of dc motor using sliding mode…………………………….1
1.1 Introduction……………………………………………………………………………………1
1.2Motivation……………………………………………………………………………………...1
1.3Sliding mode control…………………………………………………………………………...1
1.3.1 Switching function………………………………………………………………………2
1.3.2 Control law design………………………………………………………………………4
1.4 Example: DC motor speed control using sliding mode control……………………………….5
1.4.1 Simulink model of sliding mode control for dc motor….………………………………7
1.5 Simulation results……………………………………………………………………………...8
Chapter 2 Modeling of digital dc-servo motor…………………………………10
2.1 Introduction…………………………………………………………………………………..10
2.2 Mathematical modeling of dc servo control…………………………………………………10
2.3 Model estimation process of dc-servo motor………………………………………………...13
2.3.1 Starting a new session in the system identification tool GUI……………………………...14
2.4 Modelling of digital dc-servo motor…………………………………………………………15
2.5 Chapter summary…………………………………………………………………………….18
Chapter 3 PID controller design for dc-servo motor…………………………19
3.1 Introduction ………………………………………………………………………………….19
3.1.1 Objective…………………………………………………………………………………19
3.2 Tuning of PID controller……………………………………………………………………..20
3.2.1PID tuning of Ziegler and Nichols rules………………………………………………….20
3.3.2 Design PID controller for dc-servo motor……………………………………………….22
3.3.3 Finding the value of gain parameter…………………………………………………….24
3.3.4 Design PID controller where output as angular position………………………………..26
Chapter 4 Experiment study on the digital servo motor set-up……………...29
4.1 Introduction………………………………………………………………………………….29
4.1.1 Overview…………………………………………………………………………………29
4.1.2. Working Procedure of Servo……………………………………………………………29
4.2. Description of servo setup………………………………………………………………….30
4.3. Mechanical unit of servo set-up…………………………………………………………….32
4.4. Digital unit of servo set-up…………………………………………………………………33
4.5. PID control of dc servo motor………………………………………………………………34
4.5. Results………………………………………………………………………………………35
Chapter 5 Conclusion and Future work………………………………………………………36
References……………………………………………………………………….37
Fig no.
1.1
LIST OF FIGURE
Page no.
Simulink model of dc motor
7
1.2
Simulink model of dc motor using sliding mode control
7
1.3
output of dc motor using SMC
8
1.4
Control input of motor
8
1.5
Phase portrait of the motor
9
1.6
Sliding surface
9
2.1
Circuit diagram of dc motor
10
2.2
System identification toolbox
14
2.3
Running motor with voltage as input and output as speed.
15
2.4
System identification toolbox after importing input and output
15
2.5
Input output response of importing data.
16
2.6
Transient response of the model
16
2.7
Estimation of process model
17
2.8
Simulated and measured output model of dc-servo motor
18
3.1
Basic control configuration
19
3.2
block diagram of proportional controller
20
3.3
Ziegler-Nichols second method corresponding time
21
3.4
open loop response of dc motor
22
3.5
Root-locus for open loop transfer function
23
3.6
PID Controller for dc-servo motor
25
3.7
output of DC-servo motor
25
3.8
Measured and simulated output model of dc motor
26
3.9
Bode plot of the open loop transfer function of dc motor
27
i
3.10
Block diagram of PID controller
28
3.11
Angular position output of dc-servo motor
28
4.1
Digital unit of servo set-up
31
4.2
Servo Mechanical Unit 33-100
32
4.3
Digital Unit 33-120
33
4.4
Experimental set-up for PID controller
34
4.5
Simulink model of a general PID controller
34
4.6
Reference voltage of the motor
35
4.7
position outputof the motor
35
4.8
Error output of the motor
36
4.9
Output of the PID controller on dc servo set-up
36
ii
Table no.
List of Table
Page no.
1.1
Parameter of dc motor
5
3.1
Ziegler-Nichols second method tuning rules
21
iii
ABSTRACT
Dc motor has been widely utilized as a part of much mechanical provision for their exact, basic
and nonstop control attributes. We have different controller for control dc motor speed/position
PID,PI and sliding mode using software Matlab and experiment set up. The brushless dc motor
extensively used for control system and industrial application because small in size, high
efficiency and high torque density Design PID controller to get fast step response. The PID
controller gives very good response and the controller further tuned to decrease overshoot and
steady state error. In industries PID controller are better than other controller. PID controller is
not difficult to tune and modest. PID control technique is unable to balance out the nonlinear
plants or in the vicinity of limited however high instabilities. Sliding mode control strategy is
powerful to matched vulnerabilities and the fancied execution is accomplished. The chattering is
principle impairment of SMC.
This thesis an extensive study to control speed/position of dc motor by different Controller like
PID, Sliding mode in Matlab simulation as well as experimental Study on dc servo set up. The
system identification technique is used to get the accurate transfer function of dc motor system
identification is the technique where we give some input to the motor and get output
corresponding input and output we get the process model with measured and simulation mode
through is model get the best fit percentage result after find the transfer function of plant we have
design the different controller to control the speed/position of the motor. We have design PID
controller for both speed and position control.
iv
SPEED CONTROL OF DC MOTOR USING
SLIDING MODE
CHAPTER 1
1.1INTRODUCTION
To definition of any control issue there will ordinarily issue interferes with the genuine plants
and to plan the numerical model for controller. The bungle may be comes because of the
unmodelled flow, variety in the framework model. The specialist needs to beyond any doubt that
the aftereffect of the controller need to capacity to process the obliged execution levels in handy,
for example, plant and model bungles. To defeat this issue we have strong control system. The
hearty controller configuration is the alleged sliding mode control.[1][9]
1.2MOTIVATION
Everybody is determined by inspiration. My aspiration to be a necessary a piece of the pioneers
of present day advances tempted me to pick designing as my vocation. Cutting edge human
progress is computerized development. Here very nearly each and every control movement is
carried out digitally.as I am a M.tech scholar of control and automation specialization I have
enormous enthusiasm toward computerized & control field. Adjoining that I have experienced
the different control framework course in my undergrad and additionally postgraduate which
make more push in this field.
1.3 SLIDING MODE CONTROL
The sliding mode control chips away at the rule of variable structure control. In numerous
zones for the commonsense issue to lessen the dismissal and the craved reaction are obliged so
SMC is connected such framework whose conduct are direct and additionally non-liner the
primary work of the sliding mode outline the controller. Variable structure framework is
1
depicted as the shut circle the state passes or re-passes through the surface is called exchanging
surface or sliding surface and consistent lies on that surface, when the slip and subsidiary of
failure is zero. This kind of movement is called sliding movement when the trajectory proceeds
onward the surface is inside controlled by called comparable control.[1][9]
In Monsees (2002) introduce the following way to design sliding mode control
Consider a linear plant
̇
Where
and the matrices
is controllable. The control law
Where
the matrix has full rank and
is define as
is positive constant and
is the switching function
For design the switching function we have to finding matrix
this is define switching
function.
This gives the desired performance in sliding mode to find the transformation matrix
̃
Transform 1.4 into a regular form,
Where ̃
̃
̃ ̃
̃ ̃
̃̇
̃
̃
̃
̃
̃
̃
̃
̃̇
̃
̃
2
The equation 1.3 is transformed into a new coordinates
̃ ̃
Where ̃
̃ ̃
̃
Defining the sliding surface as
the controller which bring the system in the sliding mode,
From the equation (1.7) the state variable ̃ is
̃
̃
̃ ̃
The matrix ̃ is assumed to be invertible. Substituting equation (1.8) into the (1.5) and (1.6)
result in dynamics of sliding mode
̃̇
It is necessary to choose product of matrix ̃
(̃
̃
̃
̃ )̃
̃ . The common choice is
̃
̃
The matrix ̃ is invertible. The Eigen value of the matrix is ̌
̃
̃
̃
can be put some
state feedback law e.g pole placement method and matrix ̃ will be substitute. From the
equation (1.3) the matrix
is
[̃
̃]
3
1.3.2
To find the controller in sliding mode control to the system from equation (1.5) and (1.6)
Occur in finite time. The transformation matrix is
̃
[ ]
[̃
̃ ]̃
Apply transformation (1.12) on the system (1.5) and (1.6) bring the system in the form of
̃̇
̇
̃ ̃
̃
̃ ̃
̃
̃
The control law is chosen as
The
is the continuous component and
is the discontinuous are given by
̃
̃
̃
To study stability the Lyapunov function is defined
This function can be apply to reaching law
̇
̇
| |
η is positive Constant. Substituting (1.14)-(1.17) into (1.19) result is
| |
| |
4
Dividing (1.20) by | |the condition (1.20) is
| |
This condition is always satisfied when
and
.which is used to convergence of the
trajectory to the switching surface. If this condition is met, the closed loop system will reach the
sliding mode in finite time.
1.4 Example: DC motor speed control using sliding mode control
The parameter of dc motor is given in the table 1.1 [15]
Table 1.1 parameter of dc motor
Transfer function given below:
…..( 1.22)
From the equation 1.1 we have
.…...(1.23)
The equation in term of time domain is
̈
̇
...….(1.24)
Now consider
5
…….(1.25)
Now, this system is converted to controllable canonical form:
̇
̇
……(1.26)
Now the error between reference speed and actual speed is given below:
.…(1.27)
̈
̇
…..(1.28)
Now, The Switching function of the sliding mode is:
̇
̇
̇
.…(1.29)
̈
̇
The equivalent control is
̇
.….(1.30)
The total control law is
……(1.31)
Where
6
From equation 1.31
̇
…..(1.32)
1.4.1 Simulink model of sliding mode control for dc motor
1
In1
2
1
s
-K-
In2
Gain
Integrator
0.8
1
s
-K-
Gain4
Gain3
1
Integrator1
Gain2
Gain5
0.6
-K-
Out1
Gain1
0.8
Figure 1.1 Simulink model of dc motor
Scope1
Scope2
25
Constant
-K- Gain2
-K- Gain3
In1
100
-K-
1
Out1
-K-
w
In2
Constant1
Gain
Sign
Gain1
dc motor
Derivative
du/dt
Scope
Figure 1.2 Simulink model of dc motor using sliding mode control
7
1.5 Simulation results:
output of DC motor using SMC
speed(rad/sec)
100
50
0
0
0.1
0.2
0.3
0.4
0.5
Time(s)
control input u
Figure1.3 output of dc motor using SMC
500
0
-500
0
0.1
0.2
0.3
Time(sec)
0.4
0.5
Figure1.4 Control input of motor
8
phase portrait
10000
𝑥
x2
5000
0
-5000
0
20
40
60
80
100
x1
Figure1.5 Phase portrait of the motor
sliding surface S
4
1 x 10
0
-1
-2
0
0.1
0.2
0.3
Time(sec)
0.4
0.5
Figure1.6 sliding surface
9
MODELING OF DIGITAL DC-SERVO MOTOR
CHAPTER 2
2.1INTRODUCTION
In this chapter the mathematical and mathematical modeling of digital dc servo is done. The
mathematical modeling is done by system identification tool box. The system identification
toolbox gives us the transfer function of the plant after finding the plant transfer function we
have design the PID controller to control the both angular velocity and angular position of the
motor.
2.2 MATHEMATICAL MODELING OF DC SERVO CONTROL
Dc servo motor is broadly utilized for modern and domesticated reason. It is important to build
the numerical model of DC servo motor here we are utilizing armature control DC motor to
control speed and position of Dc motor. In armature control of DC motor the resistance
inductance
connected in series and voltage
and
is representing the back emf of DC servo
motor. The motor parameter and variable define as follow. Consider armature control dc motor
shown in fig2.1[15]
Figure2.1 Circuit diagram of dc motor
10
.
The air gap flux
Where
is the constant
Where
is the constant
The field current is kept constant in armature control dc motor, the becomes
Where
is motor torque constant
Now,
11
Where
is the back emf constant
Apply KVL in the circuit
The torque equation is given as
Taking Laplace transform of equation, assuming zero initial condition, we get
Here, we can see that
is the angular position of the shaft and
is applied voltage.
12
2.3. MODEL ESTIMATION PROCESS OF DC-SERVO MOTOR
We are finding the model of dc-servo position control by the help of system identification
toolbox in Matlab system identification session represent the total progress, including ant data of
set and process model in system identification tool box.
The following steps in the system identification GUI is:
 Running the motor with some known input and save the input and output in
Matlab workspace.
 In Matlab command window type ‘ident’ and start a new session in system
identification toolbox.
 In Matlab workspace import data corresponding the starting time and sampling
interval.
 Specify the data of estimation and validation.
 Select the process model by different model technique.
 We can choose the type and order of model to identify.
 After above step, we can check model output, transient response, frequeny
response,noise spectrum, pole zero location. The maximum best fit percentage
will give us good accuracy and for mode matching.
 Export model to the Matlab workspace for further analysis.
13
2.3.1. A NEW SESSION IN THE SYSTEM IDENTIFICATION TOOL GUI
In the system identification toolbox GUI start a new session while, typing the command in
command window ‘ident’
On the other hand, we can begin another session by selecting start > toolbox >system
identification> framework recognizable proof tool stash GUI in the Matlab desktop this
movement open framework ID GUI
Figure2.2 System identification toolbox
We can additionally begin another session by shutting the current session utilizing File > Close
session. This tool kit prompts you to spare your current session on the off chance that it is not
effectively spared
14
2.4 MODELLING OF DIGITAL DC-SERVO MOTOR
The model estimation is done by the system identification toolbox in matlab. We have run the
motor with some known input (voltage) and collect the output (angular velocity) whlie
performing the experimet on dc-servo set-up.
Signal
generator
Feedback servo trainer
digital unit 33-003
DAC
Feedback servo trainer
digital unit 33-003
ADC
Speed
Figure2.3 Running motor with voltage as input and output as speed.
Figure2.4 System identification toolbox after importing input and output
After collect the input output from the dc-servo motor .we import the data from system
identification toolbox. Seen figure 2.4
15
Input and output signals
y1
Speed(rad/sec)
10
5
0
-5
-10
0
100
200
300
400
500
600
700
800
900
1000
0
100
200
300
400
500
Time
600
700
800
900
1000
voltage
Inputu1
10
5
0
-5
-10
Figure 2.5 Input output response of importing data.
In the dial box figure2.7 we can enter how many poles to estimate and delay and zero to
numerator to the transfer function of the process model. we can also add the integrator to the
process model. Moreover, we can give all the poles as real and under-damped (complex pole)
from the above case the process model is best fit in third order model P3U in figure 2.8.In figure
2.8 we can see that the output of process model exactly follow the input of the process model.
16
Step Response
0.9
0.8
Speed(rad/sec)
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-20
-10
0
10
20
Time
30
40
50
60
Figure2.6 Transient response of the model
Figure2.7Estimation of process model
17
Figure 2.8 Simulated and measured output model of dc-servo motor
The open loop transfer functions of the dc-servo motor whereas angular velocity is the output
and voltage as input given below.
2.5 CHAPTER SUMMARY
This chapter gives mathematical modeling of dc-servo motor and a detail of model estimation of
system identification toolbox.
18
PID CONTROLLER DESIGN FOR DC-SERVO
MOTOR
CHAPTER 3
3.1 INTRODUCTION
Proportional-integral-derivative (PID) controllers in commonly used in process control industries
so, we have various process for tuning PID controller to get performance index for system
dynamics response the for determine the parameter of PID dynamic response of the plant.
The PID control info is the error between the coveted yield and the real output. The error is
controlling by the controller PID to handle a summon sign for the plant as indicated by the
relationship.[12]
(
∫
In time domain
Where
)
= proportional gain
= integral time constant
= derivative time constant
R(s)
E(s)
U(s)
Plant
C(s)
Figure3.1 Basic control configuration
3.1.1 Objective
In this chapter we have control the speed and angular position of dc servo motor by the help of
PID controller. we have find the PID gain by the tuning method of Ziegler and Nichols after
finding the PID gain the controller is design to control the angular velocity and angular position
of the motor.
19
3.2 TUNING OF PID CONTROLLER
The methodology of the selecting the controller parameter to meet given execution determination
is known as controlling tuning. Zeigler and Nichols principle tuning of PID controller intending
to set the worth of focused around step reaction as well as focused around the relative increase
result is barely steady when the corresponding consistent is utilized .
3.2.1METHOD FOR TUNING OF ZIEGLER AND NICHOLS RULES:
i.
First method
ii.
Second method
First method : Obtain the response of the plant through an experiment with unit step response
.If the plant does not involve any dominant complicated conjugate pole, then such unit step
response look in s-shaped formed type.[12]
Such response curve may be generated experimentally or form dynamic simulation of the plant.
Second method
First we set the value of Ti   and Td  0
We increase the value of proportional gain from 0 to critical gain K cr till first sustained oscillate
come.[12]
KP
PLANT
Figure 3.2 block diagram of proportional controller
20
Ziegler-Nichols tuning coefficients for P, PI, and PID controllers are given in Table 3.1
Type of
controller
0
0
Table 3.1 Ziegler-Nichols second method tuning rules
0
Figure 3.3 Ziegler-Nichols second method corresponding time
21
3.3.2DESIGN PID CONTROLLER FOR DC-SERVO MOTOR
From the system identification toolbox we have find The open loop transfer function of the dcservo motor whereas angular velocity is the output and voltage as input given below:
a (s)
0.8775

Va (s) 7.022s3  17.13s 2  10.24s  1
1
Speed(rad/sec)
0.8
0.6
0.4
0.2
0
0
5
10
15
20
25
Time(sec)
30
35
40
45
50
Figure3.4 open loop response of dc motor
From the figure we can see that the output of dc motor is not perfectly match to the step input
so, to match the output to the input we need controller here, we have design PID controller to
control the angular velocity of the motor.
22
Figure3.5 Root-locus for open loop transfer function
We can see in the figure the graph cut the imaginary axis at gain 6.77 at the frequency 6.14
where, gain 6.77 is the critical gain where we the sustained oscillation. From the value of gain
( K cr ) and the frequency we can find the value of proportional gain, integral gain and derivative
gain by the help of Ziegler and Nichols tuning method .
23
3.3.3FINDING THE VALUE OF GAIN PARAMETER K p , K d , K i .
Now, we have K cr = 6.77 and corresponding cr = 6.14
From the table tuning of Ziegler Nichols the parameter of PID is given below:
K p =0.6 K cr
Ti = 0.5 Pcr
Td = 0.12 Pcr
Where, Pcr 
2
cr
From the above value we have find the gain from the table 3.1
K p =16.3362
Pcr =5.1927
Ti =2.5964
Td =0.6491
Ki 
Kp
Ti
=6.2919
K d  K pTd =10.6039
24
Figure3.6 PID Controller for dc-servo motor
2
speed(rad/sec)
1.5
1
0.5
0
0
5
10
15
20
25
Time(sec)
Figure3.7 output of DC-servo motor
25
3.3.4 Design PID controller where output as angular position.
Now, controller PID design where output as angular position and input is applied voltage. so
from the system identification toolbox we find the open loop transfer function .
Figure3.8 Measured and simulated output model of dc motor
We can see that from the figure 3.8 the most effective match proportion is from third
order therefore currently we have open loop transfer perform is given below.
(s) is the angular position of the dc-servo motor and Va (s) is the applied voltage of dc motor.
26
Figure3.9 Bode plot of the open loop transfer function of dc motor.
From the figure we can see that the gain margin is 16.2 corresponding frequency is 6.02.
We know,
Where K cr is the critical gain.
16.2=
6.45
From the value of critical gain the tuning parameter find from the table.by Ziegler Nichols
technique we have
27
= 3.56
= 0.1
0.56
Figure3.10 Block diagram of PID controller
100
position(rad)
50
0
-50
-100
0
5
10
15
20
25
Time(sec)
Figure3.11 Angular position output of dc-servo motor
28
EXPERIMENT STUDY ON THE DIGITAL
SERVO MOTOR SET-UP
CHAPTER 4
4.1. INTRODUCTION
In this chapter we have study and perform experiment on digital servo set-up where we have
control the position and speed of the motor.
4.1.1 Overview
A servo is an engine that is joined to a position input gadget. By and large there is a circuit that
permits the engine to be told to go to a specified "position". An exceptionally basic utilization of
servos is in Radio Controlled models. Servos are to a great degree valuable in mechanical
technology. The engines are little and are to a great degree effective for their size. It likewise
attracts power corresponding to the mechanical burden. A gently stacked servo, thusly, doesn't
devour much vitality. Servos are built from three fundamental pieces, an engine, a reaction
gadget, and a control board. The engine, through an arrangement of riggings, turns the yield shaft
and the potentiometer at the same time. The potentiometer is bolstered into the servo control
circuit and when the control circuit catches that the position is right, it stops the engine.[6][10]
4.1.2. Working Procedure of Servo
The servo engine has some control circuits and a potentiometer (a variable resistor, otherwise
known as pot) that is joined with the yield shaft. The potentiometer permits the control hardware
to screen the current point of the servo engine. In the event that the pole is at the right point, then
the engine stops. In the event that the circuit finds that the plot is not right, it will turn the engine
the right bearing until the edge is right. The yield shaft of the servo is fit for voyaging some place
29
around 180 degrees. Typically, it is some place in the 210 degree range, yet it differs by maker.
An ordinary servo is utilized to control a rakish movement of between 0 and 180 degrees. A
typical servo is mechanically not equipped for turning any more remote because of a mechanical
stop based on to the fundamental yield gear. The measure of force connected to the engine is
relative to the separation it needs to travel. Along these lines, if the pole needs to turn a vast
separation, the engine will run at full speed. On the off chance that it needs to turn just a little
sum, the engine will run at a slower speed. This is called relative control. The control wire is
utilized to impart the point. The point is controlled by the term of a beat that is connected to the
control wire.[6][10]
4.2 DESCRIPTION OF SERVO SETUP
The framework involves three units which permit the examination of the essentials of simple and
advanced servo control:
 A Mechanical unit
 An Analogue Unit
 A Digital unit
The mechanical unit conveys a force enhancer, dc motor and tachogenerator; outright and
incremental computerized encoders include and yield simple potentiometers, an advanced rate
and voltage presentation and a sine, square and triangle waveform generator for testing purposes.
The Analog Unit conveys a four information error amplifier, a controller with autonomous P, I
and D channels and offices for single enhancer recompense circuits.[6][10]
The Digital Unit conveys ADC and DAC for indicator change, exchanging and multiplexing
circuits, encoder yield and presentation and liner and PWM engine drive. Access is given to the
information and yield potentiometers empowering an extensive variety of straight and
computerized frameworks to be examining.
Disclosure programming is accommodated utilization with the Digital Unit. Interconnection
between units is by lace link and framework interconnection is by stopped patch heads on the
simple or advanced units, which convey clear realistic formats.
30
Figure 4.1 Digital unit of servo set-up
A force supply is incorporated which gives the greater part of the fundamental dc voltage
supplies needed by the framework. The framework is adaptable. For simple control showing just
the Mechanical and Analog units are needed. For Digital control showing just the Mechanical
and Digital units are needed. These alternatives are accessible independently. In this task I
obliged just mechanical Unit and Digital unit in light of the fact that these two units are just
utilized within Digital servo examination.
31
4.3. MECHANICAL UNIT OF SERVO SET-UP
The mechanical unit comprises of an open-board design get together convey the mechanics of
the framework in addition to its supporting gadgets as indicated in fig.4.2. The electromechanical
segments embody dc engine, a simple tachogenerator, simple enter and yield potentiometers,
outright and incremental advanced encoders and attractive brake. The supporting gadgets
includes: the force intensification; a low recurrence sine, square and triangle waveform generator
for testing purposes; encoder perusing hardware and LCD velocity show and DVM.The force
supply for the basics mentor to this unit.[6][10]
Reference input
Motor
Angular position
Optical encoder
Optical encoder
Figure 4.2 Servo Mechanical Unit 33-100
32
4.4. DIGITAL UNIT OF SERVO SET-UP
The Digital unit goes about as the interface between the Mechanical Unit and a PC, or perfect
microcomputer as indicated if fig. 4.3.
Figure 4.3 Digital Unit 33-120
Specification:
 Give access to have PC, or perfect microcomputer.
 8-way includes and yield transports.
 Additional control lines accessible.
 ADC and DAC for liner framework operation.
 Liner or PWM motor accessible.
 LED showcase of incremental and outright encoders.
 Manual fixing with machine controlled arrangement and multiplexing.
 Switched deficiencies circulated through framework.
33
4.5 PID CONTROL OF DC SERVO MOTOR
Test set-up for PID controller is indicated in fig.4.4.the PID controller is intended for our wanted
DC servo motor exchange capacity inferred from framework system identification tool kit more
detail depiction given at chapter2 the reaction of the PID controller for our plant is discovered to
be steady.[10]
Signal
Generator
s
Feedback servo trainer
digital unit 33-003
DAC
Feedback servo trainer
digital unit 33-003
ADC
Position
Figure 4.4. Experimental set-up for PID controller
Figure 5.5 represents the Simulink model of a general PID controller. Input to the model is a
square wave of amplitude 50v and frequency of 0.05 Hz with sampling time of 0.05sec.
Figure.4.5.Simulink model of a general PID controller
34
Reference voltage
4.5 Results:
Position (rad)
Figure 4.6.Reference voltage response of the motor
Figure 4.7. position response of the motor
35
80
60
40
error
20
0
-20
-40
-60
-80
2000
4000
6000
8000
10000
Time(sec)
12000
14000
16000
18000
Figure 4.8 Error output of the motor
100
Output
50
0
-50
-100
0
0.2
0.4
0.6
0.8
1
Time(sec)
1.2
1.4
1.6
1.8
2
4
x 10
Figure4.9 Output of the PID controller
36
CONCLUSIONS AND FUTURE WORK
CHAPTER 4
Conclusion:
We have seen that the in PID controller the overshoot is high and setting time take more time to
settle down to overcome this problem we have deign the sliding mode control by the help of
sliding mode control we can reduce the overshoot as well as settling time. We conclude that the
sliding mode control is more robust and gives quick reply to the system.
Scope for future work:
The Digital servo framework in which we lived up to expectations is just good with MATLAB
(version 6.5).this is the real hindrance of this framework we found. Because of this contrarily
issue we are not equipped to perform some development tests that are accessible in higher
request version of MATLAB.
37
REFERENCES:
[1] Vadim I. Utkin, “Variable structure systems with sliding modes”, IEEE Transactions on
Automatic Control, vol. AC-22, pp. 212–222, April 1977.
[2] John Y. Hung, Weibing Gao and James C. Hung, “Variable structure control: A survey,”
IEEE Transactions on Industrial Electronics, vol.40, no.1, pp.2-22, February 1993.
[3] K.D. young, V.I. Utkin and U. Ozguner, “A control Engineer’s guide to sliding mode
control,” IEEE Transactions on Control System Technology, vol.7, pp.328-342, 1999.
[3] Hung, J. Y., W. Gao and J. C. Hung (1993), “Variable Structure Control: A Survey,” IEEE
Transactions on Industrial Electronics, v.40, n.1, pp.2-22.
[4] J. J. Slotine, “Sliding controller design for nonlinear systems,” Int .J. Contr., vol. 40, no. 2,
pp. 421-434, 1984.
[5] J. Nilsson, ‘Real-time control systems with delays’, Ph.D. dissertation, Lund Institute of
Technology, 1998.
[6] The feedback servo 33-120 manual, 2008.
[7] J. Eker and A. Cervin. A Matlab toolbox for real-time and control systems co-design. In
Real-Time Computing Systems and Applications, 1999. RTCSA '99. Sixth International
Conference on, 1999.
[8] A. Sabanovic and D. Izosimov, “Application of Sliding modes to induction motor control,”
IEEE Trans. Industiy Applications, vol. LA-17, no. 1, pp. 41-49, 1981.
[9] C. Edwards and S. K. Spurgeon, Sliding mode control: Theory and Applications. Taylor and
Francis,1998.
[10] Bollepally Raju a Mtech research ‘Time delay compensation schemes with application to
networked control system’ at National Institute of Technology Rourkela 2009.
[11] Srinibas Bhuyan a Mtech research, ‘Development and control of networked servo system’ at
National Institute of technology, Rourkela 2011.
38
[12] Katsuhiko Ogata, Modern Control Engineering, Upper Saddle River, NJ, Prentice Hall,
2002.
[13] W.Gao and J.CHing,”Variable Structure Control of Nonlinear System, A new approach”,
IEEE Trans, Ind. Elec. Pp. 45-55, Vol.40 N 1, 1993.
[14] D.S. Lee, M.J.Youn, “Controller design of variable structure systems with nonlinear sliding
surface,” Electronics Letters, vol. 25, no. 25, pp.1715-1716, 1989.
[15] Uma maheswaraoo.ch and Y.S.Kishore babu,’Sliding Mode Speed Control of DC Motor’
ieee conference on communication system and network technologies.2011
[16] K. K. Zhil’tsov, Approximation Methods of Variable Structure System Design. Moscow:
Nauka, 1974 (in Russian).
39
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Related manuals

Download PDF

advertisement