Special Invited Lecture: Improving the Performance of MEMS Actuators Using Feedback Control

As MEMS actuators are used for increasingly challenging applications, greater reliability, speed, and performance accuracy are needed. Increasing demands are reaching a point where mechanical design improvements alone cannot provide further improvements in performance. Alternative approaches, such as open-loop or closed-loop control driving strategies, must be used instead. The presence of system vibratory modes has introduced additional challenges for controller design. This talk will explore applications where closed-loop feedback control strategies can be successfully used to improve MEMS actuator performance. The talk focuses on electrostatic MEMS actuators. Experimental results are provided to show the effectiveness of the feedback control design methods. We design a light intensity control system for a MEMS variable optical attenuator (VOA) that speeds up the response. We design a controller for lateral instability in electrostatic actuators that allows the use of the full range of actuator motion. We design a controller that stabilizes electrostatic microactuators and avoids pull-in, allowing the effective utilization of the entire capacitive gap. We compare the performance of open-loop and closed-loop control strategies, and present experimental results to address the comparative issues involved.