ROS2 workspace example

Description

This is a sample ROS2 workspace, with a package and two main dependencies:

1. v4l2_camera: camera publisher (/image_raw) - follow this guide
   Install using sudo apt install ros-foxy-v4l2-camera
2. vision_opencv: set of tools with cv_bridge to convert image_raw data to opencv (and other things) - follow this guide
   Install using sudo apt install ros-foxy-vision-opencv
3. mypkg: simple image subscriber/publisher created following this guide

Sequence to create a new package

Typical workspace folder structure:

workspace_folder/
    src/
      package_1/
          CMakeLists.txt
          package.xml

      package_2/
          setup.py
          package.xml
          resource/package_2
      ...
      package_n/
          CMakeLists.txt
          package.xml

First, create a package with ros2 pkg create --build-type ament_cmake <package_name> (or ament_python).

Then, customize package.xml with info about license, developer, name...

Create your publisher/listener inside workspace/src/mypkg/mypkg folders (i.e. create a mypkg_function.py script).

If using python, edit setup.py adding the correct entrypoints:

entry_points={
        'console_scripts': [
                'talker = mypkg.mypkg_function:second',
                'listener = mypkg.mypkg_function:main',
        ],
},

Build using colcon, then launch.

Note: you can also use cmake to properly setup a package before building it; i.e. specifying a compiler (c++/g++/gcc) and install directories.

Useful commands

First you have to source the ROS2 environment (your script is in /scripts/ros2_launch.sh).
Display active nodes: rqt_graph ;
Build a package (or all) colcon build --packages-select mypkg (or colcon build) ;
Remember: source installed packages: source install/local_setup.bash from within the workspace;
Launch your custom node: ros2 run mypkg listener ;
Launch via multicast: ROS_DOMAIN_ID=13 ros2 run mypkg publisher ;

Additional notes

Original forklift model: downloaded from here