Modelling and control of an electrostatically actuated torsional micromirror

Abstract

This work aims at developing control algorithms for an electrostatically actuated torsional micromirror, extending the operational range of the device to a full 90 • tilt angle. The analytical model of the micromirror equipped with an additional vertical electrode is established. Since the geometrical extent of the device is comparable to the air gap, the effect of the fringing field is also incorporated into the model. It is shown that the considered system is differentially flat and, based on this property, a closed-loop control scheme is constructed for both scanning control and set-point control. In addition, the desired performance can be specified through reference trajectories, allowing the control system tuning to be performed in a systematic way. The simulation results demonstrate the advantage of the developed control scheme over the constant voltage control.

Adjusting the Vibratory Response of a Micro Mirror via Position and Velocity Feedback

“…The nonlinearities must be also taken into consideration when building more comprehensive models of the micro systems. For example, the actuation force of the micro system was modeled as a nonlinear function of angular displacement and time, in earlier studies (Juneau et al, 2003;Ataman and Urey, 2004;Zhu et al, 2006). As a result, the governing differential equation in the simulation model becomes nonlinear with time-varying coefficients.…”

A Characteristic Study of Micromirror with Sidewall Electrodes

“…Define the coordinate system. Although the models for vertical electrode configuration are deduced in (Toshiyoshi and Fujita 1996;Zhu et al 2006), there is no existing models to describe 2-DoF configuration. The coordinate systems are defined: 1) global coordinate system (XYZ) and 2) body-fixed coordinate system (xyz).…”

“…As a result, micromirrors with sidewall electrodes are proposed in Pu et al (2004). Although the effect of bottom electrodes is well understood (Dickensheets and Kino 1998;Toshiyoshi et al 2001;Yeow et al 2005), there is no theoretical model to describe the effect of sidewall electrodes on a biaxial micromirror (Toshiyoshi and Fujita 1996;Zhu et al 2006). The purpose of combining sidewall electrodes with bottom electrodes is to increase the electrostatic force on the micromirror plate.…”

Closed-loop control of a 2-D mems micromirror with sidewall electrodes for a laser scanning microscope system

“…Direct open-loop control system suffers poor transient behavior such as long rise time and large overshoot. For this reason, several feedback approaches have been used to provide further enhancements in transient response and positioning performance, such as adaptive control [13] , PID control [14] , active control [15] , flatness-based control [16] , and nonlinear control [17,18] . In practice, perturbations resulting from the imperfections due to the fabrication process and the operational stochastic disturbances are inevitable.…”