Dealing with low resolution data for speed PID

[Jared Russell]

Originally Posted by Ether

Problem with measuring elapsed time between consecutive encoder pulses is: manufacturing tolerances of the spacing of pulses on the encoder wheel can result in an excessively noisy signal if you measure only one pulse.

I have found that the most common source of this problem with encoders is that the A and B lines are not exactly 90 degrees out of phase and I am trying to measure the time between two consecutive transitions in "x4" mode (rising A -> falling B for example). I have had good luck with measuring successive transitions in "x1" mode (rising A -> rising A) because the disks themselves are usually pretty well made(at least in the case of US Digital S series and Grayhill 61/63 series optical encoders).

Worst case you can average the last N measurements and be able to trade off phase delay with smoothness.