Backdriving Motors connected to DRV8825

Support Motor controllers/drivers and motors
1

Hello,

I have some of the DRV8825 motor controller boards (2133), as well as the micro metal step motors (3073 and others) with encoders (3081) mounted on them. I want to use the gearbox / motor / encoder as a high resolution input for a DIY Follow Focus. (Essentially, a human will be turning the motor by hand, and I will be counting the encoder ticks for adjusting focus position.)

It would be ideal if the motor (which is now acting like a generator) can be attached to a motor controller, so that the focus wheel can provide either a ‘force feedback’ or otherwise be animated (for instance A to B transitions).

Are there any caveats or design tenets that need to be followed when putting together a hand turned motor connected to a motor controller? Anything further that needs to be followed if the system is being powered by a lipo battery?

Thanks in advance!

2

Hello.

The DRV8825 is intended to drive bipolar stepper motors and does not have any features that would allow it to work well with a brushed DC motor like the micrometal gear motor you mentioned. Though we have many brushed DC motor drivers, they do not utilize encoder feedback directly and must be integrated with a system using something like a microcontroller to read the encoder. The RoboClaw motor controllers we carry can perform position control, but they do not have any force feedback features built in.

Also, generally we do not recommend stalling or backdriving our micrometal gear motors as the motors could overheat or the gears could be damaged. We think they are probably not appropriate for your application.

-Nathan