Bi-directional extension of the travel range of electrostatic actuators by open loop periodically switched oscillatory control

Pull-in instabilities occur in the dynamics of several classes of electromechanical systems which are of interest in connection with a number of actuator technologies. We describe a gap-closing type electrostatic actuator for which pull-in instabilities occur, and we propose and analyze a novel structure and an open-loop oscillatory control design to stabilize and extend the operation range of a parallel plate actuator bi-directionally; for both gap-closing and gap-enlarging. Our approach involves averaging theory and the design of an averaged potential function around whose critical points the dynamics of the controlled system are organized. An oscillatory stabilizing control law is designed by parametrically shaping the averaged potential. Practical features of the control law are discussed, and performance of the controlled system is shown to be robust with respect to disturbances.