README.md

About this repo

• Stores my notes on RoboMaster ROS tutorials and development.

Dev Notes

• Robot base movement - cmd_vel publishing
• Joystick controller - cmd_vel mapping

Learning Notes

• Package
  • Create a package
  • Compile the new package
• Node Introduction
  • What is a node?
  • Code
  • Run
  • Check node information
• Node Communication
  • How to communicate?
  • Publisher
  • Subscriber
• ROS Namespace
  • Public
  • Private
• Topic
  • Basic Commands - Topic
• Message
  • Write a .msg file
  • Use the defined msg type
  • Basic Commands - Message
• Service
  • Write a .srv file
  • Basic Commands - Service
  • Service Class
  • Server
  • Client
• Topic and Service
• Launch file
  • Write a .launch file
  • Launch
• Parameter
• Can modify during runtime

Structure of ROS

• Folder (stack)
  • Subfolder (package)
    • Node (programs)
      • Service (functions)

Preparation

Creating a catkin workspace

• Under the desired directory:

  • mkdir -p ~/catkin_ws/src
  • cd ~/catkin_ws/
  • catkin init / catkin_make
    • Complete the stack stucture
    • Note: if encounter: catkin: command not found
      • sudo apt-get install python-catkin-tools

• Under ~/.bashrc:

  • source ~/catkin_ws/devel/setup.bash

  ~/.bashrc:

  • source /opt/ros/melodic/setup.bash
    • Find where ROS is installed on your computer
    • Enable us to use ROS functionalities (e.g.: roscore, rosrun)
  • source ~/catkin_ws/devel/setup.bash
    • Activate the catkin workspace
  • Note:
    • only one catkin_ws can run at one time, running source on a second catkin_ws will automatically deactivate the first one and activate the second.
    • To switch between workspaces, either source the corresponding setup.bash file (targetWS$ source devel/setup.bash) , or modify the ~/.bashrc file.
    • Run source ~/.bashrc after modification on it.

• In VSCode:

  • Generate task.json under .vscode
    • Terminal > Configure Default Build Task > catkin_make: build
  • Teminal > Run build task
    • Difference between catkin_make: errors will show under the "problems" tab in VSCode