Mechanism Analysis and System Identification of the Quadrature Error in MEMS Gyroscope

Abstract

This paper discusses error mechanism and experimental system identification of the quadrature error present in Tsinghua University MEMS vibratory rate gyroscopes. The magnitude and stability of the quadrature error are both of concern because they corrupt the measurement of the actual input rate. The stiffness matrix of suspension beams and a three-mode dynamics model of gyroscope structure are developed and the analysis demonstrates that structure imperfections result in the quadrature error, which is generally considerably larger than Coriolis-induced rate signal. The gyroscope dynamics and structure parameters are identified by modal experiment and frequency response function matrix. The experiment results from twenty gyroscope samples demonstrate that structure imperfections are main reasons resulting in the quadrature bias of the gyroscope, including anis-elasticity of suspension beams, and stiffness coupling between drive axis and sense axis. The identified structure parameters will also contribute to future laser trimming for reducing the quadrature error of gyroscope.