Nonlinear Control Of Microelectromechanical Systems (MEMS) Devices

Abstract

Different actuation principles have been developed for MEMS but electrostatic actuators are the most common. A significant drawback in the use of electrostatic actuators for some applications is their nonlinear voltage to position characteristics. Analog operation of these devices requires the use of feedback to stabilize and linearize them. Controlling and optimizing the operation of electrostatic controllers using feedback requires the establishment of the complete and accurate dynamical model of the device. In this thesis, we show how an optical switch driven by a MEMS electrostatic comb drive is controlled to guarantee its performance, stability and reliability for use in optical networks. Analog control of electrostatically actuated MEMS devices is also discussed and analyzed. A simple 1-DOF actuator model is used to derive a nonlinear control scheme which eliminates "snap through" and improves the dynamic performance of electrostatic microactuators. Finally, a novel fiber-optic pressure sensor design that employs a misaligned fiber-axis with respect to diaphragm center is discussed. It is shown that such a configuration increases the sensor sensitivity and pressure measurement range appreciably.