Filter-based control for parallel plate micro electrostatic actuators

In this paper, a filter-based nonlinear control strategy for parallel-plate micro electrostatic actuators is designed. The proposed control technique utilizes the measurements of the micro actuator´s movable plate displacement and the device internal charge. The information of the micro actuator´s movable plate velocity is utilized as well in the control synthesis but since it is difficult to be measured, filtered signals are designed and utilized to facilitate the control development. A Lyapunov-based analysis is presented which proves that a desired time-varying displacement of the micro actuator´s movable plate is accurately tracked. The proposed nonlinear controller is capable of controlling the movable plate beyond the pull-in boundary that is one third of the capacitive gap. Representative numerical simulations are introduced to demonstrate the performance of the proposed filter-based nonlinear control strategy in accurately tracking the deflection of the micro electrostatic movable plate within the entire capacitive gap. Finally, a comparison with a standard PID controller is also presented to demonstrate the effectiveness of the proposed control design.