Stabilization of dual-axis micromirrors beyond the pull-in point by integral sliding mode control

Abstract

Electrostatically actuated dual-axis micromirrors suffer from inherently nonlinear electrostatic torques, leading to the problem of ‘pull-in’ for large tilt angles. Stabilization beyond the pull-in angles of this device poses a great challenge for researchers. This paper presents a servo mechanism based on integral sliding mode control (ISMC) for this purpose. The control scheme comprises an integrator controller which is designed to achieve zero steady-state error, and a sliding mode controller which is designed for overcoming the instability. The effectiveness of the closed-loop system is illustrated by simulation and verified by experimental results. Both of them show that the dual-axis micromirror can be stabilized beyond the pull-in point with the proposed approach.