Open vs. Closed-Loop Control of the MEMS Electrostatic Comb Drive

The purpose of this paper is to address the issue of driving the very small scale (1.5 times 1 mm) comb drive (actuator). Two approaches are available, input signal shaping approach that drives the comb drive in open loop, and a closed loop approach. Position is measured by optical sensor. We compare the two approaches using both experimental and simulation results. First, the description, model, and experimental setup of the actual device are given. It is followed by simple parameter identification. Input shaping open-loop techniques are addressed first. It is followed by closed-loop approach. Finally, the comparison between two approaches, sensitivity issues, and reflections on the design of the device itself are given