Robust sliding-mode control of electrostatic torsional micromirrors beyond the pull-in limit

This paper presents high-resolution control of torsional electrostatic micromirrors beyond their inherent pull-in instability using robust sliding-mode control (SMC). SMC enables compact realization of a robust controller tolerant of device characteristic variations, non-linearities, and many types of inherent instabilities. Robustness of the control loop is demonstrated through extensive simulations and measurements on MEMS with a wide range in their characteristics. Control of two-axis gimbaled micromirrors beyond their pull-in instability with overall 14 milli-degrees pointing accuracy is confirmed experimentally.