SunFounder Smart Video Car Kit Raspberry Pi DIY Robot Kit for Kids Adults Compatible Vehicle Audio & Video Installation User Manual

Preface
About SunFounder
SunFounder is a technology company focused on Raspberry Pi and Arduino open source
community development. Committed to the promotion of open source culture, we strive to bring
the fun of electronics making to people all around the world and enable everyone to be a maker.
Our products include learning kits, development boards, robots, sensor modules and
development tools. In addition to high quality products, SunFounder also offers video tutorials to
help you make your own project. If you have interest in open source or making something cool,
welcome to join us!
About This Kit
The kit is suitable for the Raspberry Pi model B+, 2 model B and 3 model B.
In this book, we will show you how to build the smart car via description, illustrations of physical
components, and schematic diagrams of circuits, in both hardware and software respects. You
may visit our website www.sunfounder.com to download the related code and view the user
manual on LEARN -> Get Tutorials and watch related videos under VIDEO, or clone the code on
our page of github.com at
https://github.com/sunfounder/Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi
Free Support
If you have any TECHNICAL questions, add a topic under FORUM section on our website
and we'll reply as soon as possible.
For NON-TECH questions like order and shipment issues, please send an email to
[email protected]. You're also welcomed to share your projects on FORUM.
Contents
Introduction ........................................................................................................................................ 1
Components ...................................................................................................................................... 2
i.
Acrylic Plates ........................................................................................................................ 2
ii.
Mechanical Fasteners......................................................................................................... 3
iii.
Drive Parts ............................................................................................................................. 4
iv. Electrical Components ....................................................................................................... 5
v.
Self-provided Parts............................................................................................................... 8
Assembly ............................................................................................................................................. 9
i.
Mechanical Assembly......................................................................................................... 9
1.
Car Assembly ................................................................................................................................ 9
2.
Mount Assembly ........................................................................................................................ 22
3.
Mount + Car ................................................................................................................................ 27
ii.
Electrical Module Assembly ............................................................................................. 29
iii.
Circuit Connecting ............................................................................................................ 30
Electrical Components Basics........................................................................................................ 40
i.
Raspberry Pi ........................................................................................................................ 40
ii.
Step-down DC-DC Converter Module ........................................................................... 41
iii.
Servo .................................................................................................................................... 41
iv. DC Motor Driver ................................................................................................................. 42
v.
USB Wi-Fi Adaptor .............................................................................................................. 42
vi. Servo Controller ................................................................................................................. 43
vii. 18650*2 Battery Holder...................................................................................................... 43
Software Related ............................................................................................................................. 44
i.
Download and Install Raspbian on a TF Card ............................................................... 44
ii.
Get Source Code .............................................................................................................. 44
iii.
Basic Software Environment ............................................................................................. 45
Operation on PC ............................................................................................................................... 45
Prepare the PC for remote ............................................................................................................ 45
Operation on Raspberry Pi ............................................................................................................ 46
Install python-dev, python-smbus ............................................................................................... 46
Setup I2C port .................................................................................................................................... 46
MJPG-streamer .................................................................................................................................. 46
iv. Calibration .......................................................................................................................... 49
Preparation ......................................................................................................................................... 49
Start Calibration ................................................................................................................................. 52
Motor Adjustment ............................................................................................................................. 52
Turning Adjustment ........................................................................................................................... 52
Mount Adjustment ............................................................................................................................ 53
Get on the Road! .............................................................................................................................. 54
v.
Program Analysis and Explanation ................................................................................. 58
Abstract ................................................................................................................................................ 58
Introduction of Socket..................................................................................................................... 58
1.
Server ............................................................................................................................................. 58
2.
Client.............................................................................................................................................. 60
Summary ........................................................................................................................................... 62
Introduction
The SunFounder Smart Video Car Kit for Raspberry Pi is composed of Raspberry Pi, step-down DCDC converter module, USB camera, DC motor driver, and PCA9685-based servo controller. From
the perspective of software, the smart car is of client/server (C/S) structure. The TCP server
program is run on Raspberry Pi for direct control of the car. And the video data are acquired and
delivered via the open source software MJPG-streamer in a real-time manner. The TCP client
program is run on PC to send the control command. Both the client and server programs are
developed in Python.
The smart car is developed based on the open source hardware Raspberry Pi and integrates the
knowledge of mechanics, electronics and computer, thus having profound educational
significance.
1
Components
i. Acrylic Plates
2
ii. Mechanical Fasteners
Parts
Name
Qty.
M1.2*4 self-tapping screw
8
M2*8 screw
6
M2.5*6 screw
16
M3*10 countersunk screw
2
M3*8 screw
8
M3*10 screw
6
M3*30 screw
4
M4*25 screw
2
M2.5*8 copper pillar
16
M3*24 copper pillar
8
M2 nut
6
M2.5 nut
16
M3 nut
20
M4 self-locking nut
2
F694ZZ flange bearing
2
3
iii. Drive Parts
Parts
Name
Qty.
Tower Pro
Micro Servo
3
SG90
4
Gear reducer
2
Driven wheel
2
Active wheel
2
iv. Electrical Components
Parts
Name
Raspberry Pi
Model B+
Qty.
1
16-Channel 12-bit
PWM driver
1
(servo controller)
L298N DC motor
driver
Step-down DC-DC
converter module
5
1
1
USB Wi-Fi
adapter
USB camera
18650*2
1
1
1
Battery holder
6
Ribbon
1
USB cable
1
Cross socket
1
wrench
Cross
1
screwdriver
Heat shrink
tubing
20cm jumper wire
1
4
(F to F)
10cm jumper wire
5
(F to F)
10cm jumper wire
(M to F)
20cm jumper wire
(M to M)
7
2
2
v. Self-provided Parts
The following parts are not included in the set.
Parts
Name
Qty. Needed
18650 3.7V
rechargeable
2
Li-ion battery
TF Card
8
1
Assembly
i.
Mechanical Assembly
1. Car Assembly
Front Wheels
a) Fasten the F694ZZ flange bearing, driven wheel and following acrylic plates with an M4*25
screw and an M4 self-locking nut in the way as shown below. Use the cross socket wrench to
fasten the M4 self-locking nut.
Pay attention to
the direction of
this plate
b) When completed, the assembly c) Bear in mind that DO NOT over-tighten the nut or
should look like the figure below.
else the wheel cannot turn flexibly. Neither too loose,
in case the gap between the parts is too large.
9
a) Fasten the F694ZZ flange bearing, driven wheel and following acrylic plates with an M4*25
screw and an M4 self-locking nut in the way shown as below.
Pay attention to
the direction of
this plate
b) When completed, the assembly
should look like the figure below.
c) Bear in mind that DO NOT over tighten the nut or
else the wheel cannot turn flexibly. Neither too
loose, in case the gap between the parts is too
large.
Note: The acrylic plates next to the bearing in the two wheels are of opposite faces, as shown in
the following figure.
10
Back Half Chassis + Rear Wheels
a) Assemble the following two acrylic
plates
b) When completed, the assembly should
look like the figure below.
c) Assemble the gear reducer, the active wheel and following acrylic plates with two
M3*30 screws and M3 nuts.
d) When completed, the assembly should look like the figure below.
11
e) Assemble the following two acrylic
plates
f) When completed, the assembly should look
like the figure below.
g) Assemble the gear reducer, the active wheel and the previously assembled part with
two M3*30 screws and M3 nuts.
h)
When completed, the assembly should look like the figure below.
12
Back Half Chassis + Copper Standoffs
a) Assemble 4 M3*24 copper standoffs and
4 M3 nuts into the acrylic plate part as
shown below.
b) When completed, the assembly should
look like the figure below.
Servo Adjustment
Before installing the servos, we need to adjust them to 90°. But why? The reason is that the servo
we used rotates in a range of 0-180°. If the rotating in usage is beyond the allowed range, the
servo may burn out. So before assembly, we need to adjust the servo shaft to 90°, and install the
servo based on the instructions, ensuring the assembly won't go beyond limitations.
Method 1
The easiest way is to connect the servo to a Raspberry Pi and PCA9685 PWM driver board, or an
Arduino board, and give the servo PWM signals so as to adjust the shaft to 90°. So it'll be done!
Method 2
There is a tricky way to do this, as the method 1 may be a little troublesome. Follow the tutorial
below carefully. It may seem complex, but once you start, you will find it quite simple.
Prepare a servo and a 1-arm rocker arm.
a) Insert the rocker arm into the servo shaft,
rotate the arm counter-clockwise until it
cannot move. It may be like this:
13
b) It may be in the position as shown
below:
c) No matter which position the rocker arm is in,
just pull it out softly, and do not rotate the shaft.
Then insert it in the position as shown below,
which is in the middle of the servo or a little
down:
Don’t worry about the precision. Fine
adjustment will be made by software in
calibration part. Just try to put it in an
approximate position.
d) Rotate the rocker arm clockwise until it
cannot move. It should be in a position
close to this:
If what you get is quite different from that,
you need to retake the steps above.
e) If it’s almost that position, you can rotate the
rocker arm counter-clockwise to the upper
position.
Thus the servo shaft will be in the 90° position. For fine adjustment, just leave it to related code.
At last, remove the rocker arm without moving the shaft. If the shaft moves just a little, it is
acceptable. Minor mistaken movement needs no adjustments.
You're recommended to take all those three servos out from the package for adjustment prior to
assembly, so the whole process will be simpler.
14
Steering Linkage + Servo Rocker Arm
a) Connect the following acrylic plate to the second hole of the rocker arm (see the figure
below) with an M2*8 self-tapping screw.
The M2*8 self-tapping screw is contained in the package of the servo; it is one of the two
longest screws.
Also the rocker arm is packaged together with the servo. Note: Be careful with the screw
of pricking your fingers.
b) Tighten the screw first, then loosen it a little to ensure the Steering Linkage’s movement, the
assembly should look like the figure below.
15
Steering Servo + Upper Plate
a) Connect the servo to the acrylic plate below with two M2*8 screws and M2 nuts.
Pay attention to the face of the plate. Refer to the small hole in the plate as pointed by the
arrow in the following figure.
b) When completed, the assembly should look like the figure below.
Note: The servo should be placed with its output shaft toward the front of the plate (see the
following figure).
16
Steering Servo + Steering Linkage
a) Connect the following parts with an M2*4 screw.
The M2*4 screw is contained in the package of the servo; it is the shortest of the screws in
the package.
b) When completed, the assembly should look like the figure below.
Pay attention to the orientation during the assembly. If you find any error in the assembly,
do not try to turn the axis of the servo; instead, you should disassemble it and then assemble
the parts again.
17
Front Chassis + Upper Plate
a) Connect the following parts and wheels with M3*8 screws, M3*24 copper standoffs and
M3 nuts, 4 for each.
b) When completed, the assembly should look like the figure below.
18
Upper Plate + Copper Standoffs
a) Assemble 16 M2.5*8 copper standoffs and 16 M2.5 nuts into the acrylic plate as shown
below.
b) When completed, the assembly should look like the figure below.
c) The view from the back of the plate:
19
Back Chassis + Upper Plate
a) Connect the two assembled parts with 4 M3*8 screws.
b) When completed, the assembly should look like the figure below.
c) The view from the back of the plate:
20
Battery Holder
a) Assemble the battery holder to the plate below with 2 M3*10 countersunk screws and 2
M3 nuts.
You can thread a ribbon through the plate below, so it will be easy to remove the battery,
which is up to you.
b) When completed, the assembly should look like the figure below.
c) The view from the top is as follows. Now the car assembly is completed.
21
2. Mount Assembly
Plates + Servo Rocker Arms
a) Connect the rocker arm of the servo to
the acrylic plate below with 4 M1.2*4
screws.
b) When completed, the assembly should be
like the figure below.
The rocker arm is packaged together
with the servo.
c) Connect the rocker arm of the servo to
the acrylic plate below with four M1.2*4
screws.
d) When completed, the assembly should be
like the figure below.
The rocker arm is packaged together
with the servo.
22
Pan/Tilt Servo + Plate
a) Connect the servo to the acrylic plate
below with two M2*8 screws and M2 nuts,
and we name it "pan servo".
b) When completed, the assembly should
look like the figure below.
c) Connect the servo to the acrylic plate
below with two M2*8 screws and M2 nuts
and we name it "tilt servo".
d) When completed, the assembly should
look like the figure below.
23
Pan Servo Plate + Tilt Servo Plate
a) Connect the two plate parts together
with two M3*10 screws and M3 nuts. The
two plates should be perpendicular to
each other.
b) When completed, the assembly should look
like the figure below.
c) Connect the two parts at a right angle
with two M3*10 screws and M3 nuts.
d) When completed, the assembly should look
like the figure below.
24
Servos + Rocker Arm Plates
a) Connect the following parts without
any screws.
Top view:
b) When completed, the assembly should look like
the figure below.
Front view:
25
Before screwing, verify the rotation
angle first. Take the orientation of the
tilt (top) servo shaft as the right side, as
shown below. The pan (bottom) servo
should be able to rotate within the
range from 0 to 180 degrees, left to
right; the tilt servo should rotate also
from 0 to 180 degrees, front to back.
c) Then fasten them with an M2*4 screw.
The M2*4 screw is contained in the package of the
servo and is the shortest of the screws.
Pay attention to the orientation
during the assembly. If you find any
error in the course, do not try to turn
the axis of the servo; instead, you
should disassemble it and then
assemble the parts again. The
calibration of the servos are the same
as we've done previously in Servo
Adjustment.
26
3. Mount + Car
a) Assemble the mount part and the car with two M3*10 screws and M3 nuts.
b) When completed, the assembly should look like the figure below.
27
c) Before the next assembly, you need to check the steerability of the servos.
1) First turn the front wheels right and left; pay attention to the utmost degree of turning: the
wheels should be able to turn to a same degree towards both sides.
2) Turn the pan servo of the mount part right and left to see if its turning works normally – turning
precisely left to right or vice versa.
3) Turn the tilt servo front to back and see if it is able to turn from precisely front to back or vice
versa.
If any of the three servos fails to meet the condition, disassemble it and adjust based on Servo
Adjustment. Please DO follow the instructions to adjust the servos; or else they may get burnt in
subsequent operations!
Back
3)
1)
Right
2)
Front
Left
28
ii. Electrical Module Assembly
－ Assemble the electrical components to the car with M2.5*6 screws.
See the figure below.
29
iii. Circuit Connecting
Preview:
This is how it looks when all wiring is done. Looks complicated but don't worry! The detailed
procedures will be given below, step by step.
30
Step 1: Connect the two DC motors with the motor driver.
You may remove the L-shaped PCB connector and plug it back after wiring.
Note: It doesn't matter how to wire the motors. After all the assembly is done, if the car moves in
an opposite direction of what you control, just swap the wiring of the two motors and it will work
normally.
After wiring, it should be like this:
31
Step 2: Connect the motor driver with the Raspberry Pi GPIO port based on the following table.
Raspberry Pi GPIO Port
DC Motor Driver
Pin11
IN1
Pin12
IN2
Pin13
IN3
Pin15
IN4
32
Step 3: Connect the servo controller with the Raspberry Pi GPIO port as follows:
Raspberry Pi GPIO Port
Servo Controller
Pin 2 (5V)
VCC
Pin 3 (SDA)
SDA
Pin 5 (SCL)
SCL
GND
GND
33
Step 4: Hook up the servo that controls the car's direction to CH0 of the servo controller, and the
two servos that control the view of the camera to CH14 and CH15 respectively, as shown below:
Step 5: Connect the motor driver with the servo controller.
34
Step 6: Connect the servo controller with the step-down DC-DC converter module. For the
connector, loosen the screws, insert the wire, and then tighten the screws with a screwdriver.
The connection should be like:
35
Step 7: Connect the battery holder with the step-down DC-DC converter module and the DC
motor driver.
Note: Please DO NOT install the batteries at this step! Do it later when you've completed all the
wiring. And take care that the red wire is the power and should be connected to the anode of
the holder, when the black wire, i.e. the ground, to cathode.
+
-
Insert the four wires into two jacks of the connector, two in each. Pay attention: the red wires to
the anode of the step-down module, when the black ones to the cathode. Also DO NOT plug a
red wire with a black one into the same jack, or it'll cause a short circuit!
-
+
36
The whole picture of wiring should be like this:
37
Step 8: Connect the Raspberry Pi with the step-down DC-DC converter module, the USB Wi-Fi
adapter and the USB camera.
38
-------------- Now the circuit is completed. Congratulations! ------------The car should be assembled successfully as shown below:
39
Electrical Components Basics
i.
Raspberry Pi
The Raspberry Pi is a low cost, credit-card sized computer that plugs into a computer monitor or
TV, and uses a standard keyboard and mouse. It is a capable little device that enables people
of all ages to explore computing, and to learn how to program in languages like Scratch and
Python. It's capable of doing everything you'd expect a desktop computer to do, from browsing
the internet and playing high-definition video, to making spreadsheets, doing word-processing,
and playing games.
What's more, the Raspberry Pi has the ability to interact with the outside world, and has been
used in a wide array of digital maker projects, from music machines and parent detectors to
weather stations and tweeting birdhouses with infra-red cameras.
In this kit, we use Raspberry Pi as the core controller of driving equipment like DC motor and servo.
With the device and a camera collaborated, video data can be acquired in a real-time manner
and delivered by Wi-Fi network.
40
ii.
Step-down DC-DC Converter Module
Built based on the chip XL1509, the module converts the battery output of 7.4V to 5V, so as to
supply power to Raspberry Pi and the servo. As a DC to DC converter IC, the chip has an input
voltage ranging from 4.5V to 40V and generates an output voltage of 5V with a current of as
high as 2A. Please note: only when the input voltage is up to 6.5V, a 5V output can be supported.
iii.
Servo
In this smart car, one servo controls the direction of the car, and the other two, the movement of
the camera between X axis and Y axis, thus defining the coverage of the camera. A servo is an
automatic control system composed of DC motor, reduction gear set, sensor, and control circuit.
It defines the rotation angle of the output shaft via delivering specific PWM signals.
Generally, a servo supports a maximum rotation angle of the shaft (like 180 degrees). It differs
from a common DC motor in the rotation mode: a DC motor rotates by circle when a servo
rotates in a certain degree and does not rotate in a round circle. Also, the former is used for
power supply by its whole-circle rotation, while the latter is applied to controlling the rotation
angle of an object (like joints of a robot).
41
iv.
DC Motor Driver
As the name suggests, the module is used to drive DC motors. The driver is built based on L298N.
As a high-voltage and large-current chip for motor driving, encapsulated with 15 pins, the chip
has a maximum operating voltage of 46V and an instant peak current of as high as 3A, with an
operating current of 2A and rated power of 25W. Thus, it is completely capable of driving two
low-power DC motors.
v.
USB Wi-Fi Adaptor
The adapter helps Raspberry Pi connect to a Wi-Fi hot spot.
42
vi.
Servo Controller
The Servo Controller is built based on PCA9685. PCA9685 is a 16-channel LED controller with I2C
bus interface. The resolution ratio of each channel is 12 bits (212=4096 levels). The controller works
in a frequency between 40Hz and 1000Hz and its duty cycle can be adjusted in a range of 0 to
100%. It provides PWM signals for the servo and controls the rotation angle of the servo.
Meanwhile, the module controls the duty cycle of the square waves output from channel 14 and
15 to regulate the rotational speed of the DC motor, so as to control the speed of the car.
vii.
18650*2 Battery Holder
The battery is to use two 18650 batteries to power the modules and servos on the car.
Note: Please pay attention to the cathode (-) and anode (+) marks inside the holder (near each
pole). Install the 18650 batteries accordingly: battery cathode to holder -, and battery anode to
holder +.
43
Software Related
i.
Download and Install Raspbian on a TF Card
If you've already installed the Raspbian system, please skip this step.
Search out the installation guide for Raspbian on the Raspberry Pi website at
https://www.raspberrypi.org/downloads/. Then download the Raspbian to your TF card and
install it.
After the installation, you may need some basic settings for the Raspberry Pi. Check out the guide
for the setting on our website www.sunfouner.com.
ii.
Get Source Code
Step 1. Download the source code directly from Github to your Raspberry Pi.
cd ~
git clone https://github.com/sunfounder/Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi.g
it
Step 2. Download the source code directly from Github to your Linux.
Method 1
Open a terminal in your Linux. Download git：
For Ubuntu/Debian:
sudo apt-get install git-core git
For Redhat/Fedora:
sudo yum install git-core git
Clone the repository from github:
git clone https://github.com/sunfounder/Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi.g
it
Method 2
If your Linux does not support installing git by yum or apt-get, download here:
https://github.com/sunfounder/Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi, or search for
Sunfounder in Github and find the repository:
Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi.
44
Click Download ZIP on the sidebar of the page, as shown below.
After download,
－ Go to the file, right click on it, and click Extract here
－ Or unzip it by command:
unzip Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi-master.zip
And then, change the folder name
mv ./Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi-master ~/Sunfounder_Smart_Video_Car_
Kit_for_RaspberryPi
iii.
Basic Software Environment
Operation on PC
Prepare the PC for remote
Install python-tk for a remote interface
sudo install apt-get install python-tk
For Windows users:
Go to the Python website www.python.org, find the latest Python 2 and install. After installation,
DO restart the computer.
45
Operation on Raspberry Pi
Install python-dev, python-smbus
Install python-dev and python-smbus:
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install python-dev
sudo apt-get install python-smbus
Setup I2C port
Run the command to open Raspberry Pi Software Configuration Tool (raspi-config)
sudo raspi-config
Enable I2C:
Select Advanced Options => I2C => <Yes> => <Ok> => <Yes>
Select <Finish>. Close the window.
If a message of rebooting appears, click <No>. Before reboot, we still need to complete some
configurations.
MJPG-streamer
Introduction
The acquisition and transmission of video data by the SunFounder Smart Video Car is fulfilled
based on MJPG-streamer.
MJPG-streamer is a command line application that copies JPG-frame from a single input plugin
to multiple output plugins. It can be used to stream JPEG files over an IP-based network from the
webcam to a viewer like Firefox, Cambozola and Videolanclient or even to a Windows mobile
device running the TCPMP-Player.
It was written for embedded devices with very limited resources in terms of RAM and CPU. Its
origin, the "uvc_streamer" was written, because Linux-UVC compatible cameras directly produce
JPEG-data, allowing fast and performant M-JPEG streams even from an embedded device
running OpenWRT. The input module "input_uvc.so" captures such JPG frames from a connected
webcam.
Installation
Plug the USB camera into Raspberry Pi, and run the command lsusb. The GEMBIRD represents the
USB camera; since it is printed on the screen, it indicates the system has recognized the camera.
lsusb
You'll see:
pi@raspberrypi:~ $ lsusb
Bus 001 Device 004: ID 1908:2310 GEMBIRD
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet
Adapter
46
Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Check whether the driver for the camera works normally:
ls /dev/vid*
You'll see:
pi@raspberrypi:~ $ ls /dev/vid*
/dev/video0
If /dev/video0 is printed, the driver is in the normal state.
Then, install the following software needed:
sudo apt-get install subversion
sudo apt-get install libv4l-dev
sudo apt-get install libjpeg8-dev
sudo apt-get install imagemagick
Compile the source code of MJPG-streamer:
cd /home/pi/Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi/mjpg-streamer/mjpg-streamer
sudo make USE_LIBV4L2=true clean all
Install:
sudo make DESTDIR=/usr install
Testing
Type in sudo sh start.sh and press Enter.
Type in the following address (replace 192.168.0.126 with your Raspberry Pi IP address) at the
address bar of your browser (Firefox is recommended):
http://192.168.0.126:8080/stream.html
Press Enter and you will see the view captured by the camera displayed on the screen in a realtime manner.
47
48
iv.
Calibration
Preparation
Run the Server
Run the calibration server on the Raspberry Pi, and wait for client to connect.
Make sure that the circuit is connected properly. Power the smart car, open a terminal in Linux.
Connect
with
your
Raspberry
Pi
via
the
ssh.
Go
to
the
directory
Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi/server, run the server cali_server.py: if the
servo gets stuck with an abnormal sound, unplug the wires at once, and redo servo adjustment
for calibration in case of further damages.
cd ~/Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi/server
sudo python cali_server.py
Then the contents of config are printed and the last line: Waiting for connection…
At this time, the car might move a bit (this is the original position set)
Run the Client
Run the calibration client on PC to connect the server on Raspberry Pi.
For Windows users:
Unzip the code package you downloaded.
Click the Start button on your computer, and type in python in the search bar, and you can find
the IDLE (Python GUI). Click it and then a window will pop up.
49
Click File -> Open -> Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi-master -> client ->
cali_client.py to open this file, modify the value of HOST for the IP address of the Raspberry Pi.
After modification, save the file and click the Run menu, and select Run Module.
For Linux users:
Open another terminal in Linux (not via ssh on your Pi). Find the sketch downloaded and edit
client/cali_client.py:
cd client/
sudo nano cali_client.py
Find the variable of HOST:
50
Enter your own address of the Raspberry Pi there. Press Ctrl+O to save and Ctrl+X exit.
Run cali_client.py:
sudo python cali_client.py
No matter what system your computer is running on, Linux or Windows, when you run
cali_client.py, a window Raspberry Pi Smart Video Car Calibration will pop up:
In the terminal remotely connected with the Raspberry Pi, the IP address of the PC will be printed.
Then you can start calibrating. Before that, take out your package box and place it vertically
with the side face to the table. Put the car onside the box and keep it balanced. The purpose is
to keep the wheels of the car off the table.
By default, the front wheels should be directly pointed towards the front; the camera on the tilt
servo should be face up no matter what directions the pan servo is pointed at. If not, you may
adjust the directions in Raspberry Pi Smart Video Car Calibration.
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Start Calibration
On the calibration UI there are three sections: Motor, Turning, and Mount.
Motor Adjustment
Click Run. The car will walk forward. Check whether both the back wheels move forward together.
If either fails to do so, your wiring may be wrong. But don't worry! You don't need to rewire; just
click the corresponding Reverse in Motor section of the Calibration window shown above. After
clicking, observe whether the wheel you just adjusted is turning forward. If the reversing works
normally, click Run again to stop the wheels from spinning.
Turning Adjustment
Currently the front wheels should be pointed at the exact front direction. But if it is not, you need
to make some adjustments. In the Turning section in the Calibration window, click the left (
)
and right (
) arrow buttons in the upper line to make fine adjustments, and those in the
lower to coarsely adjust the turning direction. Keep adjusting until the wheels is oriented to the
front exactly. Then you may place the car on the table and click Run to verify whether it runs in
a straight line. If not, perform the adjustment again till it does.
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Mount Adjustment
Now the pan servo on the car should be pointed at the exact front direction and the camera
face up. But if not, you may need to adjust them similarly. In the Mount section, there are the
adjustments for the pan servo and tilt one. Also you have two kinds of adjustments, fine and
coarse. Keep adjusting until they are pointed at the right direction.
After all the adjustments are done, click Confirm.
And the program will exit.
Then the Raspberry Pi returns to the status: Waiting for connection...
Press Ctrl + C to exit.
------------------------------------ NOW YOUR CAR IS READY TO GO! -----------------------------------
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Get on the Road!
Run the Server
Run the TCP server on the Raspberry Pi, and wait for the client to connect to control the car.
You need two terminals to run the server. One is to run tcp_client.py to receive commands to
control the car, and the other to run mjpg-streamer to provide video streams. In Windows, you
can use PuTTy to remotely log into the Raspberry Pi to start the server.
Open a terminal.
The Raspberry Pi may be still at the server directory:
pi@raspberrypi ~/Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi/server $
If not, go to the directory with cd.
cd ~/Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi/server
Then run tcp_server.py:
sudo python tcp_server.py
The server program on the Raspberry Pi will be running and waiting for the client to connect to
the Raspberry Pi.
Open another terminal. Log in the Raspberry Pi remotely, and switch to the directory under
which the program of MJPG-streamer lies:
cd ~/Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi/mjpg-streamer/mjpg-streamer
Run the program:
sudo sh start.sh
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Then the video data acquisition will start, like this:
Type in the following address (replace 192.168.0.xxx with the IP address of your Raspberry Pi) at
the address bar of your browser (Firefox is recommended):
http://192.168.0.xxx:8080/stream.html
Press Enter and you will see the view captured by the camera displayed on the screen in a realtime manner.
Run the Client
Run the client on PC to connect the server on the Raspberry Pi.
For Windows users:
Open the IDLE
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Click File -> Open -> Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi-master -> client -> client
App.py to open this file, modify the value of the HOST for the IP address of the Raspberry Pi.
After modification, save the file and select Run -> Run Module.
For Linux users:
Open another terminal again. But do not log into the Raspberry Pi remotely in this terminal. Go to
the client with cd and edit the file client.py:
Similar to changes in calibration, change the IP address in client program in your PC:
After the alteration, press Ctrl + O and save and Ctrl + X to exit.
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Then run the client program:
sudo python client_App.py
No matter what system your computer is running on, Linux or Windows, when you run the
client_App.py, the following window will appear on your screen:
You can click buttons such as Forward and Backward to control the car moving remotely. Or
click X+, X-, Y+, and Y- to control the coverage of the camera.
Note:
The server program must be run before you run the client program. Some settings must be completed
for the server before the service is done. A communication endpoint needs to be created for the
server to "listen" to requests from the client. Take the server as a receptionist or an operator of the bus
phone in a company. Once the phone and device installation is completed and the receptionist or
operator is in place, the service begins.
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v.
Program Analysis and Explanation
Abstract
From the perspective of software, the smart car is of C/S structure. The TCP server program is run
on Raspberry Pi to listen to the command from the client and control the car accordingly. The
client program is run on the PC and connected with the server through the TCP, which provides
the user with a graphical user interface (GUI) to conveniently control the Raspberry Pi remotely.
Both the client and server programs are written in Python.
Make sure that the circuit is connected properly. Power the smart car, log in the Raspberry Pi
remotely, go to the directory Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi and check the
files under it.
cd ~/Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi
ls
pi@raspberrypi ~/Sunfounder_Smart_Video_Car_Kit_for_RaspberryPi $ ls
client
datasheet
html_server i2cHelper.py
mjpg-streamer README.md
server
You can see seven files under the directory: client, datasheet, html_server, i2cHelper.py, mjpgstreamer, a file README.md, and server.
Wherein,
client, the client run on your PC,
datasheet contains some PDF files about the chip (you need to view them on PC),
html_server, the web server run on the Raspberry Pi for Android app client,
i2cHelper, a simple script to help you set up i2c on the Raspberry Pi,
mjpg-streamer, the camera driver to acquire and upload images,
README.md, an introduction file with update information,
server, the server run on the Raspberry Pi for the client on your PC.
Introduction of Socket
The C/S-structure program of the SunFounder Raspberry Pi-based Smart Car is written based on
the socket module of the Python language. Socket wraps and applies the TCP/IP and is used to
describe IP address and port. Also it is a network data structure for computer. The socket module
should be created before the communication of network applications. If the socket can be said
to be the plug of a telephone, which is the lowest layer of communication, then the combination
of IP address and ports can be said to be that of area code and phone numbers. Only having
the hardware for a phone call making is not enough. You still need to know whom and where to
call. An Internet address is composed of the essential IP address and port for network
communication.
1. Server
Here we provide a pseudocode which creates a universal TCP server for explanation. Note that
this is just one of the methods for server design. After you have a good knowledge about it, you
can alter the pseudocode as you want:
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s = socket( )
# Create a socket for the server.
s.bind( )
# Bind the address to the socket.
s.listen( )
inf_loop:
c = s.accept( )
comm_loop:
c.recv( )/c.send( )
# Listen to the connection.
# Indefinite loop of the server.
# Accept the connection from the client.
# Communication loop.
# Dialog (receiving or sending data)
c.close( )
# Close the socket of the client.
s.close( )
# Close the socket of the server (optional).
All kinds of socket can be created via the function socket.socket( ) and then bound with IP
address and port by the function bind( ). Since TCP is a connection-oriented communication
system, some settings need to be completed before the TCP server starts operation. The TCP
server must "listen" to connections from the client.
After the settings are done, the server will enter an indefinite loop. A simple, like single-thread,
server will call the function accept( ) to wait for the coming connection. By default, the function
accept( ) is a blocking one, which means it is suspended before the connection comes. Once a
connection is received, the function accept( ) returns a separate client socket for the subsequent
communication. After the temporary socket is created, communication begins. Both the server
and client use the new socket for data sending and receiving. The communication does not end
until either end closes the connection or sends a null character string.
Process Diagram of Server Program
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2. Client
It is easier to create a TCP client than to do a server. Take the following pseudocode:
c = socket( )
# Create a client socket.
c.connect( )
# Try to connect a server.
comm_loop:
# Communication loop.
c.send( )/c.recv( )
c.close( )
# Dialog (sending out and receiving data)
# Close the client socket.
As mentioned above, all sockets are created via the function socket.socket( ). Then, the function
connect( ) can be called to connect the server. After the connection is built, the dialog between
the client and the server is enabled. When the dialog ends, the client can close the socket and
the connection.
Introduction of Tkinter
Developed based on Tkinter, our client program carries graphical interfaces. Tkinter is a GUI
widget set for Python. We can develop application programs with graphical interfaces fast by
Python language based on it. It is quite easy to use Tkinter. All you have to do is to import the
module into Python.
To create and run a GUI program, take the following steps:
a) Import the Tkinter module (by import Tkinter or from Tkinter import *).
b) Create a top window object to contain the whole GUI program.
c) Create the GUI module needed on the object and enable the functions.
d) Connect the GUI modules with the code at the system back-end.
e) Enter the main event loop.
Take a simple GUI program:
Create a file Tk_test.py under the path /home:
touch Tk_test.py
Add executable privilege to the file:
chmod +x Tk_test.py
Open the file:
vim Tk_test.py
Type in the following code:
#!/usr/bin/env python
from Tkinter import *
top = Tk()
# Create a top window
top.title('Sunfounder.com')
label = Label(top, text='Hello Geeks !', fg='blue')
foreground color as blue
label.pack()
# layout
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# Create a label and set its
top.mainloop()
# main loop
Save the code and exit.
Run
./Tk_test.py
Then the following picture will appear on your screen:
Click
to close the program.
Process Diagram of Client Program
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Summary
In this manual, having learned the related components for building the car kit, you've gone
through the assembly of the mechanical parts and electrical modules with the knowledge of
Raspberry Pi as well as a brief introduction of the key parts like servo, Wi-Fi adapter, etc. Also
you've got a lot of software and coding, which lays a solid foundation for your future journey of
exploring open-source field.
The SunFounder Smart Video Car for Raspberry Pi is not only a toy, but more a meaningful
development kit for Raspberry Pi. After all the study and hands-on practice of the kit, you should
have a better understanding of Raspberry Pi. Now, get started to make better work!
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Copyright Notice
All contents including but not limited to texts, images, and code in this manual are owned by
the SunFounder Company. You should only use it for personal study, investigation, enjoyment,
or other non-commercial or nonprofit purposes, under the related regulations and copyrights
laws, without infringing the legal rights of the author and relevant right holders. For any
individual or organization that uses these for commercial profit without permission, the
Company reserves the right to take legal action.
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