A Phase Delay Suppression Method With Temperature Robustness for Hemispherical Resonator Gyroscopes Operating in the Force-to-Rebalance Mode

This article proposes a temperature-robust phase delay suppression method for hemispherical resonator gyroscopes (HRGs) in the force-to-rebalance (FTR) mode. The phase delay can lead to coupling between the quadrature control loop and the FTR control loop, which is a primary cause of the bias drift. Although methods for the phase delay identification and compensation have been reported in literatures, the effect of temperature variation on the phase delay is not considered and the effectiveness of the phase delay compensation relies heavily on the precision of the phase delay identification. In this article, a method is proposed to suppress the influence of the phase delay by aligning the azimuth of the standing wave with the stiffness axis instead of identifying and compensating the phase delay. Compared to the phase delay compensation method proposed by our group previously, the method presented in this article further enhanced the performance of the gyroscope operated under the FTR mode. Experimental results reveal that, compared to the phase delay compensation method proposed by our group previously, the bias instability (BI) of the HRG is improved from $0.009~^{\circ }$ C/h to $0.006~^{\circ }$ C/h, demonstrating an improvement of 33.3%, and the scale factor (SF) nonlinearity is improved from 47.4 to 8.6 ppm, demonstrating an improvement of 81.9%. Measurement results of the stiffness axis and SF nonlinearity across the temperature range of $- 10~^{\circ }$ C to $60~^{\circ }$ C demonstrate the temperature robustness of the proposed method. The method is straightforward to implement and yields significant improvements, providing a new approach to suppress the influence of phase delay on the performance of HRGs operating in the FTR mode.