A study of dynamic characteristics and simulation of MEMS torsional micromirrors

A theoretical model of dynamic characteristics of a torsional micromirror, considering the coupled effect of torsion and bending, is present in this paper. The step response and steady harmonic response of the micromirror are analyzed by the Runge-Kutta method. Various nonlinear phenomena are observed using the numerical simulation. When the bias voltage is applied between the micromirror and electrode plate, both the period and amplitude of the response increase as the applied voltage increases. The larger the applied voltage, the further is the shift of the mean dynamic response to the static equilibrium position. When the micromirror is excited by a harmonic voltage, the resonant frequency decreases with increasing the applied voltage and the shift of the mean harmonic steady response is very different from the step response. The mean dynamic response varies with the amplitude and frequency of the exciting voltages. And this model is verified by comparing the analytical results with ANSYS simulation results with reasonable deviations.