4.11-million Q-factor whole-angle MEMS hemispherical resonator gyroscope with 0.013°/h bias instability

The MEMS mu HRG 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 (WA) mode MEMS hemispherical resonator gyroscope (WA-mu HRG) with a high Q-factor (4.11 million) and presents a WA 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 WA 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 (ADB) drift. Experimental results demonstrate that this method can reduce the frequency difference from initial 110 mHz to 3.91 mHz. In the presence of mode matching, the ADBs drift dropped by 81.39%, from 2.586 degrees s(-1) to 0.481 degrees s(-1). Ultimately, the WA-mu HRG exhibits an angular gain of 0.695, a bandwidth of 12 Hz, and a measurement range of +/- 500 degrees s(-1). More importantly, the gyro achieves a bias instability of 0.013 degrees h(-1).