[AdamHeard]

If teams are worried about arms backdriving, stop.

If you have feedback on the arm (a potentiometer is the easiest) a simple PID loop will hold the arm steady.

If the PID loop is perfectly tuned, it may cause the motors to stall as it tries to maintain a perfect angle. If you're using the FPs (which I'm assuming you are) then you can add a slight oscillation. The oscillation can be so minimal it has no effect on scoring, and it is easy to do; Just have the programmers turn up the I slightly. In fact, anyone who has programmed a PID loop can attest to this, it's easier to make it oscillate slightly than stay perfectly still.

Read Matt Krass's paper on PID and you will have a much better description.