A Real-Time Automatic Mode-Matching Method Based on Phase-Shifted Virtual Coriolis Force for MEMS Disk Resonator Gyroscope

Processing errors can result in an asymmetric stiffness distribution within the micro-electromechanical systems (MEMS) disk resonator gyroscope (DRG), leading to mode mismatching and a consequential reduction in its mechanical sensitivity. Hence, the adoption of mode-matching technology has become an indispensable approach to address mode mismatching and enhance the performance of MEMS DRGs. This article presents a real-time automatic mode-matching method that leverages the phase-shifted features of virtual Coriolis forces. The sense mode of the MEMS DRG is stimulated by inducing a virtual Coriolis force and a phase-shifted virtual Coriolis force. The phase-sensitive demodulation method is employed to demodulate the phase-modulated signal output from the sense mode, enabling the identification and automatic control of frequency split. Additionally, the quadrature error suppression loop and force-balanced detection loop are optimized to ensure that the MEMS DRG remains sensitive to angular rate while in the mode-matching state. The experimental results show that the tuning accuracy of this method is 0.094 Hz. The bias instability (BI) and angle random walk (ARW) of the MEMS DRG are 0.583°/h and 0.0521°/
$\surd \text{h}$
in the mode-matching state, respectively. The BI and ARW of the MEMS DRG are increased by 163% and 204%, respectively, compared with those of the MEMS DRG working in the mode-mismatching state.