Nonlinear Control and Design Methodologies for Electrostatic MEMS Devices

Abstract

A method to extend the travel range of electrostatically actuated MEMS device is presented. A gap closing actuator (GCA) is used to demonstrate the method. An output (position)feedback controller is presented, along with two variable structure controllers. The forced-damping variable structure controller uses two stable structures, and the sliding mode (hybrid) controller uses an unstable and a stable structure. An adaptive controller is also presented for devices that have adequate natural damping. A design methodology for nonlinear mechanical springs is presented. The mechanical nonlinearity offsets the electrostatic nonlinearity to extend the device travel range without feedback.