Calibration and Compensation of Asymmetric Phase Error for Whole-Angle Hemispherical Resonant Gyroscope

For a hemispherical resonator gyroscope (HRG) working in the whole-angle (WA) mode, the asymmetric phase error is inevitable and has a critical impact on the accuracy of WA HRG. To eliminate the impact of asymmetric phase error, this article analyzes the influence of asymmetric phase error on WA HRG performance and proposes a novel calibration and compensation method for asymmetric phase error. First, a nonlinear error model of WA HRG considering asymmetric phase error is established using the averaging method. Then, based on the constructed error model, the influence of phase asymmetry error on the WA HRG’s drift is analyzed from both numerical simulation and experiment. The results show that the phase asymmetry error couples with the asymmetric damping and stiffness errors, which changes the drift of the original representation. Second, a novel calibration method is proposed to identify the asymmetric phase error in the force-to-rebalance (FTR) mode. Finally, the compensated HRG works in the WA mode. Using this proposed method, for a WA HRG in validation experiments, the bias instability is reduced from 0.71°/h to 0.41°/h, and the nonlinearity of the scale factor is reduced from 235 to 82 ppm, with a reduction of almost three times.