Add MuJoCo by FZI and AlgoryX

[christophfroehlich]

ros2_control system interface for MuJoCo. Not tested but looks great!

[christophfroehlich]

@Mergifyio backport humble iron

[mergify]

backport humble iron

✅ Backports have been created

• #263 Add MuJoCo by FZI and AlgoryX (backport #250) has been created for branch humble
• #264 Add MuJoCo by FZI and AlgoryX (backport #250) has been created for branch iron

[stefanscherzinger]

@christophfroehlich

Thanks for spotting and referencing that implementation! However, I'm afraid that's a little robot dependent at the moment. As far as I'm concerned, MuJoCo needs a specific configuration .xml that specifies the robot to simulate. We could adapt/change it to provide a more generic interface between MuJoCo and ros2_control so that users can simulate arbitrary robots (manipulators). I didn't continue this idea lately, but I'm interested in supporting/implementing if that's of use for the community.

[christophfroehlich]

@christophfroehlich

Thanks for spotting and referencing that implementation! However, I'm afraid that's a little robot dependent at the moment. As far as I'm concerned, MuJoCo needs a specific configuration .xml that specifies the robot to simulate. We could adapt/change it to provide a more generic interface between MuJoCo and ros2_control so that users can simulate arbitrary robots (manipulators). I didn't continue this idea lately, but I'm interested in supporting/implementing if that's of use for the community.

For the scope of this PR it is fine like it is. It should just give a reference implementation for users on control.ros.org

I have a personal interest in bringing MuJoCo and ros2_control closer due to a research project I'm working on. But I haven't tried it out yet and can't comment on the limitations. @traversaro pointed me to google-deepmind/mujoco#1432, so I think there is more work to be done to provide a seamless integration like with Gazebo (classic). Once I have the time to work on that, I'd be happy to discuss future steps to find a more general solution.

[traversaro]

@traversaro pointed me to google-deepmind/mujoco#1432, so I think there is more work to be done to provide a seamless integration like with Gazebo (classic). Once I have the time to work on that, I'd be happy to discuss future steps to find a more general solution.

Just to complement the link, I think most of people using URDF with MuJoCo either manually or automatically change the URDF before the loading in MuJoCo, or the resulting .mjcf after the conversion, and that is why there are not a lot of discussion like google-deepmind/mujoco#1432 in MuJoCo issue tracker.