closed-loop torque (current) wheel control for mecanum
 

Has anyone tried using closed-loop torque (current) control for a mecanum or holonomic bot, instead of closed-loop speed or voltage control?


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Re: closed-loop torque (current) wheel control for mecanum
 

We used closed loop current control last year to prevent wheel slip, as we did not design in wheel counters and a "free wheel" with a wheel counter from the start. You had to use the Jaguars for this, the Victor pulse rate is too slow to get a reliable average current measurement.

Eugene

Re: closed-loop torque (current) wheel control for mecanum
 

I'm not sure I understand how closed-loop current control prevents the wheels from slipping. Could you elaborate a bit?


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Re: closed-loop torque (current) wheel control for mecanum
 

The torque is proportional to the current, limit the torque to just below the torque that causes wheel slip, and your wheels never break traction. It was a good patch given the lack of wheel counters (including a free wheel) in that it only required current sensors and some software.

There are rubs:
As the speed of the robot runs up, some of the torque (measured current) is tied up in drive train friction and because of this you lose a portion of the torque that you would like applied to the wheels.
The best performance is obtained with just a little slip and you can best obtain this by using wheel counters (including a free wheel with a counter).

Eugene