Robust Controller Design for an Electrostatic Micromechanical Actuator

TL;DR: In this article, a robust feedback controller is developed on an electrostatic micro mechanical actuator to extend the travel range of it beyond pull-in limit, and two kinds of controller designs are developed for set-point tracking of the actuator despite the presences of sensor noise and external d isturbance.

Abstract: In this paper, a robust feedback controller is developed on an electrostatic micro mechanical actuator to extend the travel range of it beyond pull-in limit. The actuator system is linearized at multip le operating points, and the controller is constructed based on the linearized model. Two kinds of controller designs are developed for set-point tracking of the actuator despite the presences of sensor noise and external d isturbance. One of them is a regular fourth order Active Disturbance Rejection Controller (ADRC) and is able to achieve 97% of the maximu m travel range. And the other one is a novel multi -loop controller with a second order ADRC in an inner loop and a PI controller in an outer loop. The mult i-loop controller can achieve 99% of the maximu m travel range. Transfer function representations of both controller designs are developed. The controllers are successfully applied and simulated on a parallel-plate electrostatic actuator model. The simu lation results and frequency domain analyses verified the effectiveness of the controllers in extending the travel range of the actuator, in disturbance rejection, and in noise attenuation.