AutoTune Position

General discussion of using Roboclaw motor controllers
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willishf
Posts: 6
Joined: Sun Nov 14, 2021 9:06 am

AutoTune Position

Post by willishf » Sun Nov 14, 2021 9:38 am

I have an XYZ table use case and not clear if you should autotune the motor/encoder under load or as a free spinning motor.

If under load then have a complexity in that the X axis has two motors(one for each side) so how to autotune both at the same time.

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Basicmicro Support
Posts: 1566
Joined: Thu Feb 26, 2015 9:45 pm

Re: AutoTune Position

Post by Basicmicro Support » Fri Nov 19, 2021 12:52 pm

You can tune unloaded. This will be less accurate than loaded but in your case you have no choice on the X axis. Then you may need to make some minor adjustments to the PID values after its under load.

To test if your PID needs some adjustment, run the motor(s) back and forth to a position. If the motor(s) slow down earlier than expected the and overshoot and come back then the PID settings need some work. Assuming you use a cascaded Velocity/Postion PID you just need to adjust the Position P value. Increase it to compensate for undershoot(slowing down early) and decrease it to compensate for overshoot. If you have hunting issues(it bounced around the end point) you need to set some deadzone. Try to keep that to a minimum though since that will effect the accuracy of your positioning overall.

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