Large displacement control system beyond pull-in limitation in electro-static micro cantilever

A displacement control system for an electrostatic drive cantilever beyond the pull-in limit is newly proposed using a feedback control. The electrostatic force is linearized around a target position for the purpose to obtain a linearized equation. Based on the equation of motion, the feedback control system is designed by the optimal regulator. The system performance is evaluated by a numerical simulation using a distributed parameter system for the electrostatic drive cantilever. The simulation results show divergent states by the 2nd. resonance mode of the cantilever. To overcome the unstable state, idealistic low-pass filter is added on the feedback loop to cut off higher resonance mode. The system shows stable operation for large displacement over the pull-in limitation.