What's the right way to do mimic joints?

asked 2018-02-23 06:44:01 -0500

Airuno2L gravatar image

updated 2018-02-23 06:47:55 -0500

This question has been asked several times on this site (here and here) as well as on the ROS QA site (here and here) but its still not clear to me if mimic joints are supported in Gazebo. Or if they are, how they're suppose to be defined in a URDF.

If I use the mimic tag in the URDF joint and start Rviz, everything works as expected - if I move the parent joint, the child joint moves also. However, when I put the same model in Gazebo, it seems to ignore the mimic tag and only the parent joint moves.

I see that Gazebo has a gearbox type for it's joints, but I'm not sure how I would use that tag in a URDF since URDF joints don't have a gearbox type. If this is probably the right way to do things, could someone explain the basic idea of how to implement that?

Or, is the answer maybe that I should avoid URDF and use SDF for this portion of the robot? If so, can I include an SDF inside a URDF?

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