PROS-Car

Authors:

• 陳麒麟
• 曾裕翔
• 林庭琮
• 鍾博丞

Advising professor:

• 蘇文鈺

Car Type

Type	Description
A	Rear-wheel drive, front-wheel steering
B	Rear-wheel drive
C	Four-wheel drive with robot arm
D	Mecanum wheel

Workflow Diagram

Deprecated Warning

The image in this repository pros_car is deprecated. Use pros_ai_image instead.

The Dockerfile here is to test new feature based on ghcr.io/otischung/pros_ai_image:latest.

Feature

The docker image in this project has the following 4 features shown above.

• Keyboard
• Car_<A,B,C,D>_serial_reader
• Car_<A,B,C,D>_serial_writer
• RandomAI
• arm_reader
• arm_writer
• cv_bridge: Convert the compressed ROS image to OpenCV image format.

The Link to the other Features

pros_app contains the following features.

• RPLidar
• Camera
• SLAM

pros_AI contains Car_B_AI.

pros_AI_image is the repository which creates the entire base docker image.

Get Started

Docker

GitHub Repository

You can clone it by using HTTPS

git clone https://github.com/otischung/pros_car

Add User to Docker Group

You must add the user to the docker group to get permission for docker.

usermod -a -G docker <username>

Pull Image

You can pull the docker image by the following command. This image is automatically built by GitHub Actions CI and it contains two versions of OS type, including amd64 and arm64.

 docker pull ghcr.io/otischung/pros_ai_image:latest

Run Image

After building the image, execute the following command to run the image to become the desired container.

docker run -it --rm -v "$(pwd)/src:/workspaces/src" --network pros_app_my_bridge_network --device=/dev/usb_front_wheel --device=/dev/usb_rear_wheel --device=/dev/usb_robot_arm  --env-file ./.env ghcr.io/otischung/pros_ai_image:latest /bin/bash

• -i: The container will get stdin from your keyboard.
• -t: The container screen will show on your display monitor.
• --rm: The container will be shut down automatically when detaching.
• -v "<host/location:/container/location>": Mount the host location into container.
• --network <network_name>: Use the network you provided. We use bridge netowrk here. You can see all docker netowrk with docker network ls.
• --env-file: This will pass the environment variables defined in the specific file to the container.
• In the end, tell the container what program should be executed. We use bash in this case.

Use the Shell Script to Run the Image

We've written 2 shell scripts to run the image.

car_control_2.sh

car_control_4.sh

mediapipe.sh

A Quick Solution for Developing Containers

VSCode has these extensions, which are docker and dev containers.

After that, you can build your image from Dockerfile by launching dev containers.

• Press ctrl+shift+p, then select Dev Containers: Rebuild and Reopen.

Environment Variables

These environment variables are defined in .env.

ROS Domain ID

You may change the ID number to divide other ROS environments.

export ROS_DOMAIN_ID=1

Setting for the Speed of the Car

You can change the speed of your car via the Linux environment variable WHEEL_SPEED using the unit rad/s.

export WHEEL_SPEED=3

ROS2 Services

The Password of Cars

digitaltwin

Code

• Dockerfile
  • You may change the ID number to divide other ROS environments.

ENV ROS_DOMAIN_ID=1

• Car<A~D>_serial_writer.py
  • Send the signals to jetson orin nano, receive the signals from Car<A~D>_keyboard.py.
• Car<A~D>_keyboard.py
• Send the signal to Car<A~D>_serial_writer.py, in target_vel, index 0 is the left wheel, index 1 is the right wheel.
• if the car type is four-wheel drive, we have two lists, one contains self._vel and self._vel2 and the other contains self._vel3 and self._vel4.

# two wheels:
target_vel = [self._vel, self._vel]

# four wheels 
target_vel = [self._vel, self._vel2] 
target_vel = [self._vel3, self._vel4] 
# These two target velocities are sent through different topics

• env.py

  • When we set the USB port, if we run Car<A~D>_serial_writer.py and the terminal shows that “cannot find the desired USB port”, then you have to edit this script or check out the USB port on the car device.
  • You can run ls /dev/ttyUSB* to check your USB port number. (if there doesn’t appear any USB devices, you must exit docker, and check the USB port on the car, ttyUSB<0~3> number depends on the inserted order)
  • We've defined the name of the soft link for usb_front_wheel, usb_rear_wheel, and usb_lidar in pros_app. You may also use these rules in this container.
  • Referene

• car_models.py

  • For all received data-class types, which the behavior is like struct in C/C++.

• Open two terminals to run the car

  • We use tmux to open two terminals, pressctrl+B → shift+5 will open two terminals vertically; and press ctrl+B → shift+" will open two terminals horizontally, using ctrl+b + arrow keys to change between terminals.

  sudo apt install tmux

• run the car (open two terminals)

  • Use w a s d or other keys to control the car.
  • Press z to stop the car.
    • Note: The car will always go forward and then stop slowly in any case. This is a bug in the C++ program controlling the ESP32.
  • Press q to exit the keyboard.py.

  ros2 run pros_car_py car<A~D>_serial_writer.py

  ros2 run pros_car_py car<A~D>_keyboard.py

GTK in Docker

If you want to show GUI in docker, you need to configure your host first.

xhost +

And then run your docker image by the following command:

docker run -it --rm -v "$(pwd)/src:/workspaces/src" --network pros_app_my_bridge_network  --env-file ./.env -v /tmp/.X11-unix:/tmp/.X11-unix -e DISPLAY=$DISPLAY ghcr.io/otischung/pros_ai_image:latest /bin/bash

We've written the code above into mediapipe.sh.