Robust H_∞ controller-design for an electrostatic micro-actuator with squeezed gas film damping effects

In this article the modeling and control design aspects of an electrostatic microactuator (EmA) with squeezed thin film damping effects are presented. The modeling analysis of the squeezed film damping effect is investigated in the case of an EmA composed by a set of two plates. The bottom plate is clamped to the ground, while the moving plate is driven by an electrically induced force which is opposed by the force exerted by a spring element. The nonlinear model of the EmA is linearized in multiple operating points with respect to the plates' displacement. A robust H_∞-controller relying on LMI-theory is designed for the set of the resulting multiple operating models. The resulting controller stabilizes the set of linearized systems at the operating points. Particular attention is paid in order to examine the stability issue within the intervals of the operating points. Simulation results investigate the efficacy of the suggested modeling and control techniques.