Switching time reduction for electrostatic torsional micromirrors using input shaping

We have demonstrated switching time reduction for microfabricated, vertical comb-based electrostatic torsional micromirror actuators by suppressing residual vibration using pre-shaped command inputs. The step input is pre-shaped by pulse-impulse convolution method, one of the impulse shaping filters. The micromirror actuators tested in experiment are made of single-crystal silicon and driven by vertical comb sets in torsional direction. Before shaping the input signal, the measured 2% settling time is 25 ms with percent overshoot of 58% for a step voltage input to induce the angular motion in micromirror actuator. The improved settling time is observed to be 8ms with 5.8% overshoot when the pre-shaped input is applied. The input-shaping technique is applied to two types of microactuators with different dynamic characteristics in order to verify its feasibility on various systems, and it is experimentally shown that the pre-shaped input command successfully suppresses the residual vibration for both highly underdamped microactuators.