4.11-Million Q-factor Whole-Angle MEMS Hemispherical Resonator Gyroscope with 0.013°/h Bias Instability

Abstract The MEMS µHRG offers high potential in achieving a high quality factor (Q-factor) and the corresponding detection accuracy, thus holding significant prospects for applications in the field of high-precision inertial measurement.This paper introduces a whole-angle mode MEMS hemispherical resonator gyroscope (WA-µHRG) with a high Q-factor (4.11 million) and presents a whole-angle mode control scheme. Specifically, the paper establishes a frequency tuning technique that leverages precession angle control and quadrature control loop switching. Adjusting the quadrature control loop at special precession angles can effectively achieve alignment of the stiffness axis and reduction of frequency split.The impacts of frequency mismatch on the whole-angle gyroscope were investigated through simulations, which validated the efficacy of mode matching in improving the accuracy and performance of gyro, as evidenced by the reduction in angle-dependent bias drift. Experimental results demonstrate that this method can reduce the frequency difference from initial 110mHz to 3.91mHz. In the presence of mode matching, the angle-dependent bias drift dropped by 81.39%, from 2.586°/s to 0.481°/s. Ultimately, the WA-μHRG exhibits an angular gain of 0.695, a bandwidth of 12Hz, and a measurement range of ±500°/s. More importantly, the gyro achieves a bias instability of 0.013°/h.