Resolver compatible capacitive rotary position sensor

This paper describes a capacitive rotary position sensor that is characterized by its high compatibility with commercial resolvers. The main components are two electrode plates. Both parts are composed of simple circular or annular electrodes. The sensor is excited by two sinusoidal voltages, which are same as the excitation voltages of resolvers. These excitation voltages are applied to the stator transmitting electrodes. Then, these voltages arise on rotor electrodes by capacitive couplings. The stator pick-up electrodes detect voltages on the rotor that are amplitude-modulated due to the capacitance changes depending on the rotor position. The specifications of these signals are same as those of resolvers. Therefore, the rotor position can be calculated by the same way as resolvers. Due to the similarities with resolvers (excitation signals, generated signals and the way of calculate positions), this sensor can easily replace a commercial resolver. In this paper, the principle is verified by a prototype sensor, which shows a non-linearity error of +/-4 degrees.