Analysis of closed-loop control of parallel-plate electrostatic microgrippers

A design of a high-force-output large-deflection parallel-plate electrostatically actuated microgripper is described. This design uses polysilicon as a structural material and may be fabricated using an IC-based surface machining process. This paper shows that by using a position feedback controller, the microgripper can be stabilized in theory, which is supported by computer simulations. Preliminary data from fabricated micro-grippers also supports the mathematical model for the open loop system, although the pull-in voltages (50 V to 100 V for gaps of 80 to 100 μm²) are generally lower than predicted ones, probably due to the inherent instability of the electrostatic system. Further experiments are in progress to evaluate the open-loop system and the closed-loop system