Vibration analysis of micro mirrors for LIDAR using on-chip piezo-resistive sensor

Abstract

Novel research focuses on the use of micro scanning mirrors in mobile applications like automotive LiDAR sensors, head-mounted displays or portable micro beamer. Even under normal conditions, micro scanners are exposed to considerable environmental influences. Particularly disturbances such as shock, vibration and temperature fluctuations are relevant for miniaturized scanning systems. In this publication we show the critical environmental parameters for quasi-static micro mirrors with a staggered vertical comb drive intended for high-precision trajectory tracking control. Scanners are controlled based on a piezo-resistive position sensor feedback. Focus will be experimental shock and vibration analysis by exposure to sinusoidal and wide-band random vibration excitation as typical for automotive industry specifications. These are the most demanding requirements compared with other application fields of MEMS mirrors. The on-chip piezo-resistive sensor enables evaluation of the vibration load on the micro scanner, without any optical measurement setup. MEMS mirrors are mounted on a shaker system for characterization and are attached to a vehicle body to evaluate a real application scenario. Furthermore the performance in open-loop and closed-loop control mode is analyzed and shows very good applicability of micro scanners in an automotive environment.