Fast and precise positioning of electrostatically actuated dual-axis micromirror by multi-loop digital control

Fast and precise positioning is of great importance for electrostatically actuated dual-axis micromirror. However, this device suffers from long settling time and large cross-axis coupling. This paper reports a multi-loop digital control method to improve the positioning performance. The system is identified and a multi-loop proportional, integral and derivative (PID) controller is designed. Both the simulation and experimental results show a significant improvement for the positioning speed and precision. The settling time is shortened from 15 to 5 ms and 24 to 3 ms for x-axis and y-axis rotation, respectively. The cross-axis coupling is suppressed to a negligible level. Less than 5% maximum positioning error is obtained.