I'm looking to measure the angular velocity of an arm as it moves. It seems to be a difficult thing to research, since the term 'angular velocity/frequency' is usually reserved for other areas of circuit analysis.

I imagine something like a tachometer or a generator is most practical, but I can't find anything dealing with an incomplete rotation (i.e. about 90-120 degrees). Any help or push in the right direction would be greatly appreciated.

  • $\begingroup$ If all you need is angular velocity, a gyroscope is ideal. If you need angular position as well, use a gyroscope + accelerometer + complementary filter. $\endgroup$
    – Paul
    Jul 12, 2019 at 3:22
  • $\begingroup$ Think of the reluctor ring used for abs on cars - 12 or more teeth which gives the resolution of the partial rotation of the shaft. For 90 degrees you would get 3 pulses, depending on the start point. You could consider two 12 tooth rings offset... $\endgroup$
    – Solar Mike
    Jul 12, 2019 at 6:54
  • $\begingroup$ Any reason you can't measure position (using a potentiometer or similar) and differentiate? $\endgroup$
    – welf
    Jul 17, 2019 at 0:43

1 Answer 1


I'd use a video camera and attach a striped pattern to form a moire pattern which is easy to see in the video. Here's a link: [http://www.unappel.ch/people/emin-gabrielyan/public/070804-multi-ring-moire-indicator/]

1 [enter image description here]2


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