What methods exist to track the position of points relative to each other. Particularly what methods allow the determination of the distance between up to ten points at once. The distance determination needs to be wireless and should be able to work thru someones arm. This all needs to able to be wired up to a raspberry pi two or arduino. The measurements must be able to take place in in a few milliseconds and repeat constantly. The resolution does not have to be very good about 2 millimeters would work. All of the 10 points can be powered by wires attaching it to the micro computer. Everything will be attached to the arm by tape.
I have looked into both magnetic and RFID solutions, but I don't know enough about either to know if they would work.