World Model and robot on an external axis

[Tobimane]

Hi all,

I have a UR10e on an external linear axis. Working on a welding application using ROS2 humble and MoveIt2. I would like to know if it is possible to have MoveIt plan and execute coordinated motion for the robot on the linear axis? How would i do that? My understanding is that the scaled_joint_trajectory_controller is sending joint positions to the robot controller, so i would have to add the external axis to the controller?

Thanks for any help,
T

[urfeex]

You basically would need a ros2_control-capable driver for your linear axis. Then, your ros2_control node would load basically load two hardware interfaces, one for the linear axis and one for the arm. With that, you can define a controller controlling all 7 joints.

From a MoveIt's perspective I don't have the expertise to answer that completely, but I would assume that you generate a planning group from your linear axis fixed base to your end effector and then you should be able to plan motions for the whole thing at once.

[Tobimane]

Hi Felix,

Thanks for your swift reply!
Do i understand correctly that in this case i would have to send the control commands directly to the linear axis' controller? And that i can not just handle everything via the URs control Box?

[urfeex]

Ah, you wanted to connect the linear axis to the control box? I don't think it is possible to use that from ROS, then. There might be some workaround like using registers from the RTDE client but that would require some amount of figuring out, I guess.

[Tobimane]

Yes exactly, the axis is already connected to the control box by the integrator. i had hoped that there was an easy ros integration via the control box now that there is the world model. Seems i was wrong, I'll look into ros_control then.

Cheers,
T