A Novel Combined Sliding Mode Control of Nonlinear Optical Torsional Micromirror

MEMS optical switches based on torsional micromirror are being developed for application in optical cross connects, add-drop multiplexers, and spectral equalizers etc. The main obstacle in improving their switching performance is the long settling time and the limited torsional angle result from excessive residual vibration and pull-in phenomenon. In this paper, these two major problems are studied firstly. Base on that, a novel combined sliding mode control scheme is proposed. This method combined sliding mode control and active constant voltage actuation control not only inherits the main virtue of robustness from sliding mode control, but also further improves the dynamic performance of the micromirror system. Simulation results show that the proposed method makes the settling time reduce by 54.15%, which is less than 1ms.