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Motor encoders

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Tobi edited this page May 26, 2017 · 2 revisions

Motor encoders

Datasheet can be found here: https://github.com/TobiasWeis/pypibot/blob/master/docs/Motor_VT-E_Encoder_N20_14Pole.pdf

According to this datasheet, the magnet has 14 Poles, and outputs 7 PPR (pulses per rotation?). Disk has 7S and 7N poles, so on one pole output is high, which would explain 7 "pulses".

In practice, I measure:

  • Single rising flanks for channel a per rotation: ~374 --> 374 / 35 -> 10.7 rising flanks per rotation
  • 1.5k changing flanks per wheel rotation. Bear in mind that there is a 35:1-gear ratio between motor-rotations and wheel rotations. If I expect 7 pulses per rotation, that would equal 7*35=245 per wheel-rotation, so even I multiply this with a factor of 4 (max resolution of quadrature encoder), I still only get 980 changing flanks.
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