Real-Time Elimination of Harmonic Drift for Hemispherical Resonator Gyro Based on FRP Control Scheme

The performance of the hemispherical resonator gyroscope (HRG) in whole-angle (WA) mode is affected by the angle-dependent harmonic drift. Suppressing this drift is essential to improve its temperature stability and operational range. In this article, a novel real-time method for eliminating harmonic drift based on a forward and reverse precession (FRP) control scheme is proposed. First, the sources of harmonic drift in HRG are analyzed. The HRG dynamical equations incorporating multiple error sources are derived and analyzed through numerical simulation. Subsequently, a real-time error identification algorithm is developed and validated through simulation. Finally, a temperature experiment is conducted to validate the method. The experimental results demonstrate that the proposed method can accurately identify and compensate for errors at different temperatures, effectively suppressing the harmonic components in angular velocity by more than 97%. The bias instability (BI) of the HRG remains consistently around 0.024°/h across various temperatures, indicating strong temperature stability. Additionally, the scale factor nonlinearity (SFN) is reduced five-fold to 0.84 ppm. Most importantly, this method can be applied to all Coriolis vibratory gyroscopes to effectively eliminate their common angle-dependent harmonic drift.