Experimental Evaluation of Vibration Influence on a Resonant MEMS Scanning System for Automotive Lidars

TL;DR

This study evaluates the vibration immunity of a resonant MEMS scanning system for automotive lidars, demonstrating how vibration coupling affects performance and how control mechanisms improve stability under vibrational conditions.

Contribution

It introduces an analysis of vibration coupling in MEMS mirrors with reinforcement structures and demonstrates the effectiveness of PLL control in reducing vibration-induced errors.

Findings

Vibration coupling depends on direction and energy variation.

PLL control reduces amplitude and frequency errors by over 40%.

Simulation results align well with experimental measurements.

Abstract

This paper demonstrates a vibration test for a resonant MEMS scanning system in operation to evaluate the vibration immunity for automotive lidar applications. The MEMS mirror has a reinforcement structure on the backside of the mirror, causing vibration coupling by a mismatch between the center of mass and the rotation axis. An analysis of energy variation is proposed, showing direction dependency of vibration coupling. Vibration influences are evaluated by transient vibration response and vibration frequency sweep using a single tone vibration for translational y- and z- axis. The measurement results demonstrate standard deviation (STD) amplitude and frequency errors are up to 1.64 % and 0.26 %, respectively, for 2 grms single tone vibrations on y axis. The simulation results also show a good agreement with both measurements, proving the proposed vibration coupling mechanism of the MEMS mirror. The phased locked loop (PLL) improves the STD amplitude and frequency errors to 0.91 % and 0.15 % for y axis vibration, corresponding to 44.4 % and 43.0 % reduction, respectively, showing the benefit of a controlled MEMS mirror for reliable automotive MEMS lidars.