Harmonic electrostatic motors

This paper describes two operational harmonic electrostatic motors. A cylindrical rotor is placed inside a hollow cylindrical hole of slightly larger diameter. Electrodes on the circumference of the hole attract the rotor electrostatically and cause it to roll inside the stator. The harmonic motion of the rotor produces a ‘gear reduction’ between the electrical drive frequency and the shaft rotation rate. This motor design has the advantage of a gear reduction that increases the torque of the motor, and laso has several other advantages. First, it uses the clamping force, normally larger than the tangential force used by most electrostatic motor designs, to generate the motion. Secondly, the sliding friction between the rotor and stator, a source of hindrance for most microelectrostatic motors, helps by keeping the rotor and stator from slipping. Thirdly, this motor uses rolling surfaces that dissipate less energy in friction than sliding surfaces.