[Alan Anderson]

I apologize for giving bad advice. I have always used PD control for motor speed when experimenting, but I failed to describe the important step of post-integrating the PID output. When I've played with it, I have used the output of the PID controller as a delta, to increase or decrease the motor control. If I were to use it as an absolute motor power command, which I suppose most people would do as a matter of course, it would definitely need the I parameter!