Motors Overheating While Stopped

Questions about using encoders with the Roboclaw product line
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StaticVOiDance
Posts: 2
Joined: Sun Mar 27, 2016 11:03 am
Motors Overheating While Stopped

Post by StaticVOiDance »

I'm using the position control on the Roboclaw with quadrature encoder motors. Whenever I run a position or velocity command the system reacts properly and gets within one or two points of the target. After that the system dumps a lot of current into my motors to maintain this position. This often causes my motors to overheat and excessively wear. Also, there are no forces acting against the motors when stationary so they should consume approximately zero current when not moving. Usually I can't hear any oscillation, but sometimes I can hear a quite buzzing from the motors.

Is there some way to add a timeout to this permanent brake or to configure the PID to stop holding so aggressively?

I know I can send a duty(0) command, but I'd like configuration that doesn't rely on my controller to actively intervene. I was using a similar motor controller on another project and it had a "Brake Timeout" setting. This disabled the active braking after n seconds of no movement.

Does the Roboclaw have any similar features?
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Basicmicro Support
Posts: 1594
Joined: Thu Feb 26, 2015 9:45 pm
Re: Motors Overheating While Stopped

Post by Basicmicro Support »

1. If you are hearing buzzing the PID settings are too aggressive causing the motor to constantly be oscilating(eg having power dumped into it). Reduce the PID settings some and/or add some deadzone so when the motor reaches the 0 point and there are no external forces pushign against the motor it will stop(and power will be reduced/elliminated when idle).

2. There is no timeout for holding position. In your case the motor tuning/settings just needs to be adjusted.

3. Passive braking does not add power to the motor(eg a motor wont overheat due to braking). It shorts the motor leads together so any movement of the motor will cause it to fight against that movement. Active braking(where the motor controller pushes reverse power into a motor to slow it down faster also only happens when the motor is actually moving. Once it stops moving(reaches its set point)passive braking is used so once the motor tuning is correct you shouldn't have anymore overheating issues.

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