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Use diff_drive_controller with voltage controlled motors

asked 2020-03-18 05:37:43 -0500

fjp gravatar image

updated 2020-03-18 18:49:51 -0500

I am working on a differential drive robot using real hardware. It has two motors (wheel joints/actuators) that accept effort (voltage) values.

Is it possible to use diff_drive_controller from ROS control with these effort controlled motors? The documentation says that diff_drive_controller works with a VelocityJointInterface and not with EffortJointInterface.

Does this mean that in the hardware_interface, I have to translate the velocity commands from the controller into voltage commands for the motors? And similar for reading encoder feedback: read encoder ticks and convert them to velocity?

Are the input and output of the diff_drive_controller just velocities? How can we apply voltages to motors from the velocity values?

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Could I please ask you to stop bumping your questions?

You have a couple now which you keep editing for no apparent reason. Please don't do that.

gvdhoorn gravatar image gvdhoorn  ( 2020-03-19 03:10:17 -0500 )edit

Sorry @gvdhoorn. To my defence I am new to ROS control and would like to learn more how to use it for a hobby project. I waited more than two weeks on my first question on that topic with no activity (comment or answer). Please understand that I would like to get some answers or discussions to my questions. To me it seems that questions never get answered when not on the top :( I would really appreciate your help or from someone else. Also please let me know if my questions are unclear or too unspecific?

fjp gravatar image fjp  ( 2020-03-19 03:33:58 -0500 )edit

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answered 2020-03-22 08:53:38 -0500

fjp gravatar image

Here is a short answer from the ros-control mailing list from one of the developers:

yes and yes. Personally I consider effort to be a bit of a shapeshifter, some people use it as force, some use it for voltage...

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Asked: 2020-03-18 05:37:43 -0500

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Last updated: Mar 22 '20