[Chris Hibner]

Ether makes a good point. You'll probably also find your final speed to be less than your desired speed if you use brake mode (see my comment above on our practice robot with the bad gearbox - extra friction caused the actual speed to be less than the desired speed).

A couple of more things to note:

1) Originally, we accidentally hooked up the output of our IIR filter to the bang-bang controller "actual speed" input. The results were not very good. The shooter speed oscillated quite a bit. When you think about it, the oscillations make sense: the phase delay of the IIR filter made the controller stay at 1.0 for too long even if the actual instantaneous speed dictated that the power be 0.0 (or vice versa).

2) Speed controller resolution: Consider that a Victor speed controller has 254 discrete output states (two states are reserved). If the top speed of your shooter is about 5000 RPM (for a shot from the bridge), the best resolution you can do with a constant power command is about 20 RPM (imagine if your PID controller output a very nice steady PWM command). However, if your PWM command dithers the right amount, you can gain resolution on your shooter speed. Don't believe me? Just consider that we're getting tons of resolution to control various speeds just based on commanding 1's and 0's to the power. (I actually submitted a white paper on this topic a number of years ago, which makes me especially upset with myself that I didn't think of this type of controller until Martin mentioned it. Grrr.). Anyway, that extra dithering of the output is why I advocate not filtering the encoder signal input to the bang-bang controller.