Newbie question - kinetic art and silent steppers

Hey nerds*

I’m trying to brain a home installation which uses 4 stepper motors with the quietest driver as practical, a knockoff Arduino kit, and four of these - https://kinetrika.com/ - hanging from my ceiling.

Looking at the header on their site, it’s kinda obvious that - in order to make them do their pretty thing - the rotation has to be bi-directional, so just hanging them from a small mirrorball rotator wouldn’t be very interesting. They’d just settle on whatever homeostatic geometry each piece defaults to.

Having played with them a bit when drunk, the best action comes from timed pulses alternating clockwise/counterclockwise. I was thinking that four light-duty pancake steppers with current run in parallel to the supply and individual control to the driver would let me fine tune the alternating rotation of each, be it a sine wave, PWM, etc.

What i’m trying to avoid is a chorus of random bzzt bzzt bzzt noise in an otherwise quiet room, which would totally break the mood being set by the flow of ColorKinetics LED strips and other flow-y stuff on the ceiling.

Any help on this li’l art project really appreciated.

*in no way meant to disparage nerds coz that would be hella hypocritical :slight_smile:

Hi.

Audible noise in stepper motor systems is a common issue and there are lots of articles out there that discuss the causes of noise and ways to reduce it. One example I found with some nice scope captures is this app note from TI. The main considerations for the stepper motor driver are reducing current fluctuation while holding a step and getting a smooth sine wave pattern for the current waveform while stepping. Satisfying both those requirements generally requires picking the right decay mode. There are some drivers, like the TB67S279FTG that dynamically adjust the mixed decay timing, and theoretically result in quieter operation.

Those kinetrika are pretty mesmerizing. I would love to see the installation once you get them spinning!

-Claire

I just learned about simpleFOC from this other topic, and if you go to the simpleFOC website and scroll down to the “gimbal controller board example” you can see that he’s controlling a BLDC motor to turn to absolute positions and he’s doing it very quietly, with just a little bit of hum evident in the video. I wonder if that would work for you? Not sure about the cost of hardware or complexity of programming though.