Position - PWM - Difference Pos Neg Directions
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Basicmicro Support
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Re: Position - PWM - Difference Pos Neg Directions
It depends on the motors. On some motors the commutator is shifted so it works better in one direction than the other. I find most motors have some difference in speed at the same power in each direction. Yours is pretty drastic so I'd guess its one of those motors specifically designed to work most efficiently in one direction.
Using P only as you are you arent going to be able to compensate for the difference. You need to use D at a minimum. This way you can tune a higher P and then D will dampen the overshoot(or elliminate it entirely).
Increase P until it causes significant oscillation(or even continous oscillation) around the set point. Then back P off to 2/3rds that value. Set D to 10 times P. Make set point changes. If the movement is over damped(starts slowing down before it gets to the new setpoint(in either direction) then reduce D. Otherwise keep increasing D until set point changes stop crisply(no early slow down and no overshoot) in both directions.
Using P only as you are you arent going to be able to compensate for the difference. You need to use D at a minimum. This way you can tune a higher P and then D will dampen the overshoot(or elliminate it entirely).
Increase P until it causes significant oscillation(or even continous oscillation) around the set point. Then back P off to 2/3rds that value. Set D to 10 times P. Make set point changes. If the movement is over damped(starts slowing down before it gets to the new setpoint(in either direction) then reduce D. Otherwise keep increasing D until set point changes stop crisply(no early slow down and no overshoot) in both directions.