[billbo911]

Originally Posted by Tom Line

I'm interested in teams claiming +/- 15 rpm accuracy.

We've implemented robust PID control, and today implemented bang-bang control as a second option.

We tried 4 different high speed encoders, 2 bourn, 1 grayhill, and 1 honeywell. The noise in our 'best' situation (completely unfiltered running off the get rate from the encoder, encoder set to 1x decoding, get rate in a timed loop of 10ms) was +/- 60 RPM.

The best the bang-bang loop could do completely unfiltered was around +/- 100 RPM.

The best the PID loop could do completey unfiltered was arond +/- 80 RPM.

The PID loop spins up in 3 seconds. The bang-bang in about 1.5 seconds.

I'm curious what teams are using to measure their system to gain +/- 15 RPM accuracy without noise problems.

Should we be using an IIR or moving average filter to filter the incoming rate from the encoder to minimize noise effect on the bang-bang? (That's the geekiest sentence I've typed in a long time).

Ether pointed this out to me. Using the "Wait" timing loops is not as reliable for timing events as you might think. Read this paper call Timing is everything by team 358.
I truly believe you can get much more reliable rate control simply by switching to a "Timed Structure" instead of a "Wait" loop.