Hi all. I have a couple questions for those familiar with mechatronic stuff. I'm looking for some type of [(angle sensor) + (axle) + (Perhaps a slip ring as well)] all in one. The slip ring is necessarily going to be in the final project that I'm using it for but I could get a slip ring separately. I was particularly concerned however of how to attach an angle sensor to an axle from two separate. Regardless I need some way to combine a slip ring (electrical contact through a rotating connection) into an axle along with an angle sensor. How would I go about doing this. Moreover... I don't even have a good idea for what to buy... what sizes... what tools I'll need to build this thing.. The project is a controlled double pendulum... I'm trying to control it to swing it up and keep it inverted... here is a rough picture I drew of why I need such a complex [(angle sensor) + (axle) + (Perhaps a slip ring as well)] all in one: http://s114.photobucket.com/albums/...ction=view¤t=11-14-11DoublePendulum.png Excuse the sloppiness of the drawing... It's a concept drawing only. My intuition leads me as far as .. "Ball Bearings sound good."