Date of Award

2009

Degree Type

Thesis

Department

Electrical and Computer Engineering

First Advisor

Dong, Lili

Subject Headings

Microelectromechanical systems, Actuators, MEMS, electrostatic actuator, feedback control

Abstract

This thesis describes the mathematical modeling and closed-loop voltage control of a MEMS electrostatic actuator. The control goal is to extend the travel range of the actuator beyond the open-loop pull-in limit of one third of the initial gap. Three controller designs are presented to reach the control goal. The first controller design utilizes a regular fourth order Active Disturbance Rejection Controller (ADRC) and is able to achieve 97 of the maximum travel range. The second design also uses a fourth order ADRC, while additional modeling information is included in an Extended State Observer (ESO), which is part of the ADRC, to improve control performance. This controller achieved 99 of the travel range. The third design is a multi-loop controller with a second order ADRC in an inner loop and a Proportional-Integral (PI) controller in an outer loop. This design achieved 100 of the travel range. Transfer function representations of the three controller designs are developed. The controllers are successfully applied and simulated in a parallel-plate electrostatic actuator model. The simulation results and frequency domain analyses verified the effectiveness of the controllers in extending the travel range of the actuator and in noise attenuation

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