Enhancing the closed-loop stability of a high-Q polysilicon micro-hemispherical resonating gyroscope

Abstract

This paper presents an enhanced stability strategy for the sense mode of a force-rebalanced closed-loop polysilicon micro-hemispherical resonating gyroscope (μHRG) with a high-Q quality-factor value (15.2k). The sense mode closed-loop control including the Coriolis force and quadrature error force rebalanced loop, respectively. Specific demodulation theoretical deductions with mode-split are performed to identify a precise linear model of the sense mode open loop. The frequency responses obtained by experimental tests show good agreement with the theoretical model. The experimental results demonstrate that a bandwidth of 10 Hz and a 0.51 Hz frequency-splitting closed loop gyroscope can be extended to 86 Hz and 3.3 Hz, from 6 Hz and 0.13 Hz in the open loop. The mode-matching (0.51 Hz frequency-splitting) gyroscope with closed loop control can achieve a scale factor of 2.25 mV/°/s with a nonlinearity of 0.087%, and a bias instability of 21.8°/hr with an angle random walk of 3.1°/hr.