SECOND-ORDER SLIDING MODE OBSERVER AND CONTROL DESIGN FOR A MEMS OPTICAL SWITCH

摘要

The use of optical switch in telecommunication industry has become widespread due to its efficient advantages and has emerged application of MEMS for optical switching operation. This paper considers a nonlinear dynamics of a MEMS optical switch addressing electrical, mechanical, and optical subsystems. An inherent weakness in designing control for such systems is unavailability of switch position information at all times due to the saturated output characteristics which is aggravated by considering modeling uncertainties. In this paper, to circumvent these problems, two nonlinear observers based on the classical first order sliding mode observer (FOSMO) and second order sliding mode observer (SOSMO) are designed to estimate the state variables of the device subject to uncertainties. Finally, the nonlinear observers are utilized to design sliding mode control to maintain robust stability and tracking performances. The newly invented second order sliding mode controller (SOSMC) can remove the chattering phenomena as the main drawback of the classical first order sliding mode controller (FOSMC) as well as retaining advantages. Simulation results show that the proposed observer and control have good tracking ability and robustness against uncertainties.