[Example 9] Gazebo Classic and Gazebo

[christophfroehlich]

This is a rewrite of existing contributions #127 and #191 for the new structure of this repo.

• [x] Basic RRBot with position interface and hardware interface copied from example_1
• [x] Working example for Gazebo Classic
• [x] Working example for Gazebo
• [x] Polishing userdoc.rst

@destogl @olivier-stasse or @haider8645: I was not able to cherry pick commits from the existing PRs due to the structure rewrite, but I added you as co-authors.

To keep that example simple, I removed JTC from this example.

If merged this closes #65

[christophfroehlich]

I'm still confused which combination of Gazebo Version, ign/gz packages are released and compatible, e.g. see https://github.com/gazebosim/ros_gz/issues/300 or https://github.com/ros-controls/gz_ros2_control/issues/124

@ahcorde Do you know a working combination of binary packages for rolling+humble which we can use for this demo? Otherwise I will split this PR up into Gazebo Classic and Gazebo until everything is released properly.

Is the compatibility table in https://github.com/gazebosim/ros_gz/blob/ros2/README.md and https://github.com/ros-controls/gz_ros2_control#gz_ros2_control (no need for the humble branch? the release badges on top are pointing to ign* releases?) up to date?

[christophfroehlich]

@mhubii I gave up to create a simple demo for rolling, because back then there was not everything released for rolling. Maybe this changed, or we can at least make a working example for humble? Furthermore, gazebo classic and gazebo can't be installed in the same system? Maybe two separate docker containers would do. If you have an idea, feel free to create a new PR :)

[mhubii]

sorry for dropping these random comments^^, just stumbled upon your pr and it was helpful regardless @christophfroehlich for what I was trying to achieve.

Yes it seems only one version can be installed. But for each version individually it works for humble (didn't check rolling and new gazebo). There is only an issue where the ros 2 control gazebo plugin doesn't support multiple command interfaces if I am not mistaken.

So does this pr target rolling? Wasn't aware sorry

[christophfroehlich]

Normally we target everything to rolling and backport stuff then. But if there is a reason for a PR against humble, thats OK. If you have a working setup, can you make a new PR targeting humble? The tricky thing is describing the installation, setup of the docker, and make CI happy.

[mergify[bot]]

This pull request is in conflict. Could you fix it @christophfroehlich?

[christophfroehlich]

I close this in favor of #482 -> let's keep humble+iron as it is.