On-line identification for cantilevered electromagnetic actuators with pull-in instability using oscillatory input stabilization

Accurate model is indispensable for high precision control of gap-closing actuators driven by electromagnetic / electrostatic force. For these actuators, it is not easy to identify the precise model all along the motion range, because its mobility region is severely limited due to the pull-in instability. In this paper, an on-line identification method for gap-closing actuators is presented which enables us to stabilize the actuators using oscillatory stabilization so that the electromagnetic force can be identified even in the pull-in instability region. Both simulation and experimental results indicate that the proper model is obtained through the proposed method.