[oreocookeee]

cyberguy: i would recommend considering a lead screw for your design. the system would probably be heavier than a piston, but the functionality is very similar. the torque on the arm, or the force of the screw, would be close to if not more than that of a piston. it allows you have any position within its boundaries, and it can easily be encoded with a potentiometer. my team is planing to use one for the lower stage of our arm.

for those with experience with multi-position pistons: how firmly is the piston held at intermediate positions? the only way a normal piston stay rigid is by applying excessive force in one direction, mechanically locking it in place. if the piston is held midway between the extremes, wouldnt it act much like a pneumatic spring, or shock for that matter?