Capacitive angular position sensor

摘要

A sensor for sensing the angular position of a rotatable body including a stationary transmitter plate with at least one transmitter electrode, a stationary receiver plate with at least a first and a second receiver electrode, and a rotor formed of a dielectric material and positioned between the facing electrodes of the plates. The rotor is smaller than the plates and rotates with the rotatable body to change the capacitance between the transmitter electrode(s) and opposed receiver electrodes. The induced voltages on the receiver electrodes indicate the angular position of the rotatable body. Preferably, the sensor uses a square waveform signal and two transmitter electrodes receive signals 180 degrees out of phase. Then, four receiver electrodes forming two receiver pairs are connected so that the current flowing between each pair is measured and converted to a voltage. A lookup table compares the values of the voltage pairs to known values from calibration, giving the angular position.