A closed-loop micromotor control system

This paper describes the first ever closed-loop control system for silicon micromachined electrostatic salient-pole and wobble micromotors. Closed-loop control is achieved by sensing the position of the rotor using a low-noise capacitive scheme and by controlling the stimulation of the motor using a state machine. System level aspects such as the high-voltage drive required for the motors and practical aspects of achieving low-noise packaging are discussed. Simulation results for micromotor performance under closed-loop control and experimental results of the high-voltage drive and control logic, are presented. The scheme presented here is extremely important since it lends itself to monolithic integration of control circuitry and micromachined mechanical elements