[JohnGilb]

Initially, we had 3 closed-loop systems:

Rotational - used a gyro to keep the robot on target heading
Translational - used encoders on "follow wheels" (unpowered wheels) to gauge ground speed and keep the robot translating on a target vector
Wheel Speed - used encoders on the drive wheels themselves to achieve precise wheel speed control

After a while, we actually disabled the wheel speed, as we didn't appear to get much performance improvement from it and we were looking to save on some CPU cycles.