Super Quickly DIY Web RC Car With Python and BeagleBone

I believe that most of boys are desired to own a RC car and explore anywhere they want. Me too! So I thought of making one with my BeagleBone Green Wireless last weekend. But I faced some tough problems while making this and there was almost no tutorial for BeagleBone Web RC Car on the Internet. So I upload this instructable and hope it may help you to make your own RC Car.

Beaglebone Green Wireless is a board with Wi-Fi and easy-to-use GPIO. Therefore I decided to create a web sever on BBGW and control the car with a Web, which means that we don’t need to develop an Android APP for our smart phone, just connect to its Wi-Fi and enjoy this Web RC Car with kinds of smart phones, tablets or PC. What’s more, it’s convenient for us to extend new features on Web, such as streaming video, tracking, etc. Now Python seems the best choice for me, as BBGW supports programming with hardware in Python and Python-Flask Web microflamework is enough to create a web server.

Materials:

BeagleBone Green Wireless

BeagleBone Motor Bridge Cape

Motor Robot Car Chassis Kit with DC Motors

M3 nut and bolt

11.1V LiPo Battery

Jumper wire

In addition you will need the following tools:

screwdriver

Tape

Insert the Motor Bridge Cape to BBGW, power Motor Bridge Cape with 9-12V Battery. Then plug in BBGW via USB, connect it to Wi-Fi and open the Cloud9 IDE.

Here is the guides:

http://wiki.seeed.cc/BeagleBone_Green_Wireless/#getting-started

After that, we will start an new terminal in Cloud9 IDE.

sudo apt-get update
sudo apt-get install build-essential python-pip python-dev python-smbus git
git clone https://github.com/adafruit/Adafruit_Python_GPIO.git
cd Adafruit_Python_GPIO
sudo python setup.py install

Download the code from Github:

git clone <a href="https://github.com/Seeed-Studio/MotorBridgeCapeFirmware"> https://github.com/Seeed-Studio/MotorBridgeCapeFi...</a>

Navigate to “MotorBridgeCapeFirmware” and execute “make flash” command to flash the firmware

cd MotorBridgeCapeFirmware/ && make flash 

After a few seconds, you can see “Verification OK” information from the terminal Check if the firmware is flash well by execute following command

i2cdetect -y -r 2

And If you can’t find the I2C address 0x4b, be sure that the P9_23 Pin is High, since the P9_23 is connect to Reset pin of STM32.

Then please download the Motor Bridge Cape Driver Library from Github for a test.

cd /var/lib/cloud9<br>git clone https://github.com/Seeed-Studio/MotorBridgeCapeforBBG_BBB.git
cd MotorBridgeCapeforBBG_BBB
cp BBG_MotorBridgeCape/MotorBridge.py tests
cd tests
python DCMotorTest.py

If you can see the the red led and blue led of motor3 flashing in turn, it means that the Motor Bridge Cape works well.

<p>pip install flask</p><p>pip install flask-socketio</p><p>pip install evenlet</p>

<p>git clone <a href="https://github.com/jerryyip/bbgw_wifi_car.git"> <a> https://github.com/jerryyip/bbgw_wifi_car.git</a>...></p>cd bbgw_wifi_car/mywificar_v1.0/<p>ls
python app.py</p>

Then type 192.168.7.2:5000 or [your BBGW ip addrees]:5000 in your browser to visit the remote control website.

Click the button to check if the web socket works well(each of your click will be printed in the terminal).

Now it is time for assembling your Web RC Car! Power off the BBGW and Motor Bridge Cape, fix them on the top of chassis with tape or screw(here it is my upgraded Web RC Car in the picture with a DIY chassis and some grove modules, if you want to make one coooool chassis for your car, there is a CDR file attached at the following step).

And don’t forget to connect the DC motors to the cape. The motor on the left is connected to port 1 and the right motor is connected to port 4. I attach the battery at the back of the chassis and power the cape with a adapter and 2 jumper wire. After that, power the cape first and still plug in BBGW via USB. Open Cloud9 IDE again and run app.py. We are going to check out that if the motors works as we expect. All the action of the motors are defined in “mywificar.py”. If I need my car go straight on, I will turn the right wheel clockwise and turn the left wheel counterclockwise at the same speed, as the “goFront()” function. When you click the up arrow button in the website and the car doesn’t go straight--just circles, then you have to press the stop button and switch 2 wires in port 1 or port 4. Besides, “PwmDutyRight” and “PwmDutyLeft” are positively associated to the speed of the motor, try to increase them for a faster speed. After debugging, just rip out the USB and place your Web RC Car on the ground. Connect your phone to the Wi-Fi named “BeagleBone 05xxxxx” and visit 192.168.8.1:5000. Congratulation! Please enjoy the fun of DIY!

Next, I am going to extent patrol mode for the car and make a cool chassis for it. For the patrol mode, we need 4 Grove - Line Finder sensor to recognize the trace, a Grove - Switch for mode selection, Grove - Chainable RGB LED for mode show(Red means patrol mode and green means RC mode) and Grove Base Cape for connection.

Grove Base Cape for Beaglebone v2.0

Grove - Line Finder

Grove - Switch

Grove - Chainable RGB LED

The code is in folder “mywificar_v1.1”. Please confirm all the Grove modules are connected to the right port as what I mark in “mylinefinder.py”, “myled.py” and “myswitch.py”.

For convenience, we can set the program auto run when BBGW boot up. After that, we don’t have to plug in BBGW via USB and type command line in terminal.

Now create a file named “mycar” in /etc/init.d

cd /etc/init.d 
vim mycar
//press “i” to insert in VIM and copy the following code

#!/bin/bash
# /etc/init.d/mycar
 
case "$1" in
    start)
        echo "Starting mycar"
        python /root/bbgw_wifi_car/mywificar_v1.1/app.py &
        ;;
    stop)
        echo "Stopping mycar"
        # killall app.py
        kill $(ps aux | grep -m 1 'python /root/bbgw_wifi_car/mywificar_v1.1/app.py' | awk '{ print $2 }')
        ;;
    *)
        echo "Usage: sudo /etc/init.d/mycar start|stop"
        exit 1
        ;;
esac
exit 0

Next,

sudo chmod +x /etc/init.d/mycar
sudo service mycar start
sudo update-rc.d mycar defaults  

Now “/root/bbgw_wifi_car/mywificar_v1.1/app.py” will start automatically when BBGW boot up. What's more, you can start or stop this program with the following commands:

/etc/init.d/mycar start
/etc/init.d/mycar stop

Now I am working at video streaming on BBGW. I manage to transmit a real time video on our remote control website. That must be more interesting and exciting! We will be able to explore this world with a whole new vision.

Mjpg-streamer is my choice, but there is an unstable delay when video streaming. If you have some good ideas or if you are interested in this, please don’t hesitate to let me know! Just post your comments! Thank you!