On the differential flatness and control of electrostatically actuated MEMS

Extending the stable travelling range of actuators forms one of the central topics in the control of electrostatically actuated MEMS. Though certain control schemes, such as charge control, capacitive feedback, and input-output linearization, can extend the travelling range to the full gap, the transient behavior of actuators is dominated by their mechanical dynamics. Thus, the performance may be poor if the natural damping of the devices is too low or too high. This paper presents an alternative for the control of parallel-plate electrostatic actuators, which combines the techniques of trajectory planning and robust nonlinear control. It is therefore capable of stabilizing the system at any point in the gap while ensuring desired performances. The simulation results demonstrate the advantage of the proposed control scheme.