I am doing the inverted pendulum as a side project and I am basically weighing options on how I want this contraption to work mechanically/physically. I am kind of doing this design on the fly, and I already have my h-bridge circuitry designed and it works (i put a function generator with variable PWM and drove my Pittman motor with the board i made) I am either going to use an accelerometer or a potentiometer to measure the "levelness" of my pendulum. I am leaning towards a potentiometer because it makes more sense and seems easier with respect to knowing the starting condition of my pendulum (i'd get direct position information instead of an accelerometer of which I would need a way to gather initial conditions on position since accelerometer would not tell me this). Basically my potentiometer would feed into an A/D, and the voltage would tell my processor the angular position of the pendulum. My controller algorithm would regulate this angle. My problem comes in that I need to find the right potentiometer, and I don't have much knowledge on them. I need one that will make it possible for me to attach to the pendulum, so a knob or protrusion for me to clamp the twisty part to the pendulum would be nice. I want a very low torque one so that the friction it takes to spin it will have a minimal impact on the response of the pendulum. I also need one with atleast > 180 degrees and preferably a full 360 degrees of operation. It also needs to be fairly rugged to withstand fast and frequent movements. Also, I really would like it to be linear for the most part and have minimum hysteresis so that I can rely on ohm's law instead of a look up table. I intend to model these details in MATLAB for my system model if they have significant affect on the system. Does anyone know what common parameters I need to look out for on a potentiometer spec and if the kind of potentiometer I'm looking for even exists? I am hoping this doesn't cost me too much . .