Harmonic: Add information to reproduce demo in ros_gz_project_template

[Ryanf55]

Desired behavior

The ros_gz_project_template docs explain how to build and install, but are missing the instructions how to move the diffdrive robot in this section/

Alternatives considered

I've spent two hours trying various methods, nothing seems to move the vehicle.

With this command, the vehicle moves in RVIZ, but not in gazebo.

ros2 topic pub /diff_drive/cmd_vel geometry_msgs/msg/Twist "{linear: {x: 0.5}, angular: {z: 0.5}}"

Implementation suggestion

Add a small section to the end of the ros_gz_project_template_guide that explains the commands in terminal or through the gazebo UI to move the vehicle.

Additional context

Gazebo Version: Harmonic 8.2.0
OS: Ubuntu 22
Installation method: Binaries
Discord chat: https://discord.com/channels/1077825543698927656/1080763334384697430/1230559471659388991

Bag is attached.
rosbag2_2024_04_18-15_54_56.zip

Inspection shows the odometry is updating, so why doesn't gazebo UI show it moving?

[Ryanf55]

Honestly, I'm pretty sure this demo is completely broken on harmonic. There are numerous warnings in logs about the SDF, RVIZ has problems, and there's this PR removing the clock topic.

[azeey]

What version of ROS were you using with Harmonic and how did you set it up? Did you build ros_gz from source?

[Ryanf55]

What version of ROS were you using with Harmonic and how did you set it up? Did you build ros_gz from source?

Humble. I followed the README exactly as written, so yes, that's part of the repos file.

[Ryanf55]

I'm on discord as ryanf and available for debugging if you need.

[Ryanf55]

More info here: gazebosim/ros_gz_project_template#25

[oliviaseed]

If you are using Jazzy (recommended for Harmonic), the DiffDriveController now requires a TwistStamped message (release notes)

see an example here