[dtengineering]

You may wish to consider using the jaguars for your arm... they can take a feedback circuit from a potentiometer at the joint and then (using settings that you provide) attempt to provide sufficient power to the motor to move to and hold the position that you want.

Alternatively, labview offers a similar PID routine to control arm position. You're looking for a "closed loop feedback" system, where your driver is entering the arm position data and leaving it up to the robot (either the cRio or the Jag) to figure out how to achieve that position.

Note that this requires using the CAN bus... not the PWM cables.

Note also that this is the second step towards a solution... the first, as advocated earlier, is attempting to counterbalance the "dead weight" of the arm with springs or counterweights.

Jason

P.S. Unless your arm joint is exceeding the range of a potentiometer (usually around 270 or so degrees), I'd recommend using a pot rather than an encoder. It is simpler to just read an analog input than to zero and track an encoder.