Photosensor as encoder for bang bang.

[billbo911]

Originally Posted by Mark McLeod

So you're taking the total revs since the last time you checked the counter.
Dividing by a time constant, filtering the result, and applying a slew rate limiter?
I'm not a fan of the Counter reset applied that way. There's a window to drop counts.

Seems a bit much for flywheel.
Is the slew rate limiter to avoid extended stall time at full power for the flywheel?
P.S. I overlooked that the slew rate is probably bypassed with the False Case.

Is that really 360 counts per revolution?
I thought you only had 1?
I don't think you want that 60 or 360 applied there, but maybe I haven't grasped what you are calculating.

When I first saw the code I was surprised at how familiar it looked, then I realized, I posted it last year.

Mark, would replacing the "Reset Counter" with a feedback loop and subtracting the previous count from the current count be a more stable option?

Both the IIR filter and the slew rate limiter were placed in this code as ways to compensate for other issues.

The slew rate limiter really is only needed when using a Jaguar. The current limiting circuit in the Jag can trip if the start up current is too high. If using a Talon or Victor, this entire block of code can be bypassed or completely removed.

Honestly, the IIR filter shouldn't be used. It introduces lag into the control. I put it in there as a way to smooth out the RPM signal. I believe the main reason the signal was noisy was due to the use of a "wait" loop instead of a timed loop in the original version. In addition, we were using "Get Rate" in the original version. "Get Rate" is an instantaneous measurement that is inherently noisy. This version uses a count divided by time to determine RPM, which is a much cleaner approach. This filter can be bypassed by setting the filter strength to "0", or just deleting that section of code.

The "360" is the number of ticks per revolution of the encoder it was designed to be used with. If the encoder is just a couple of lines on a wheel and an optical sensor, the this value needs to reflect the number of lines.

Bang-Bang is a simple control system. A comparison of the current RPM to the desired RPM. If the current is at or above the desired value, then turn off the motor. If it is below, turn the motor on at full power. Anything else in the loop just clutters the process.