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We're using a stepper motor to control a knob on a piece of audio equipment. The stepper is coupled to the potentiometer shaft with a simple coupler.

Right now, in order to get to "zero" on the potentiometer, we "crank" the stepper motor -3600 steps (about one full rotation).

This creates unnecessary torque on the pot. I'm looking for a hardware solution to avoid this. Here are a few ideas I had:

  • Some sort of zero detection - Know when the knob gets to 0 and stop the stepper from turning when it reaches that point.
  • A coupler that can detect excessive force on the shaft. Basically some sort of spring loaded coupler that will "click" when the rotation gets to "zero" and close a circuit.

Also open to other ideas...

We're currently using Arduinos with Firmata firmware connected to Node.JS, but this is mostly a hardware issue.

Mark Booth
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drj
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  • Welcome to Robotics, drj. Open-ended design questions are off-topic because there are generally a very large number of approaches that are possible of solving a given problem. That said, I think the easiest approach to solve your problem would be to just read the value of the potentiometer. You could do this in about one line - while(pot>threshold) stepper--;. If there's some other problem you're having, please edit your question to reflect that. If you'd like to discuss your design options, please join us in [chat]. – Chuck Jun 19 '17 at 17:27
  • This question essentially asks how to detect a stall. For future reference, mentioning more detail of what motors you are using, what stepper motor control boards you are using, etc. would make it easier to solve your problem. – Mark Booth Jun 20 '17 at 13:56

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