What is everyone using for flywheel velocity control?

I was just wondering what everyone is using to control the velocity of their flywheel, and how they are measuring the velocity. I’m using a PD controller with a double flywheel which is working pretty good, although it seems that the Kp and Kd numbers I’m using don’t work very well when I change the target RPM of the launcher. For measuring velocity I’m using a quad encoder that is geared to the flywheel 1:7, so that the encoder can read it. Please post what kind of flywheel you have, and what you are using to control it.

Flywheel velocity control