Robust adaptive sliding mode control of a MEMS tunable capacitor based on dead-zone method

Abstract

Uncertainty in parameters of a tunable Micro Electro Mechanical System (MEMS) capacitor, as the main component of AC Voltage Reference Source (VRS), is significant to obtain a precise output voltage unaffected by disturbance and noise. Although attempts are done to craft the capacitor with desired physical specification and improve accuracy of parameters, parametric uncertainties transpire in manufacturing due to micro-machining shortcomings. First off, this paper remarks design of a Robust Adaptive Sliding Mode Controller (RASMC) and its application for the MEMS AC VRS for the first time so that it can produce a stable precise regulated output at presence of uncertainties and disturbance. Secondly, it makes a comparison between the proposed novel controller and our previously designed ASMC. The comparison reassures one of robustness at exacerbating conditions in the tunable capacitor dynamics. The novelty is employment of the dead zone-based ASMC to manage parametric uncertainty and disturbance in the MEMS tunable capacitor. It also contributes to adaptive sliding mode control of the dynamics with stiffness and damping coefficients, which are non-slowly-varying time-dependent parameters, approaching dead-zone method. Uncertainty in the plate mass besides bounded time-variant uncertainty in stiffness and damping are considered. These restrictions were not deemed in the previous design.