Self-calibration for phase shift in Coriolis vibratory gyroscope with whole-angle mode operation

Coriolis vibratory gyroscope (CVG) is an inertial instrument used for angular rate measurement. Reducing the effect of phase-locked loop (PLL) phase shift on CVG with whole-angle (WA) operation has been a challenging problem. To address this issue, a self-calibration method based on square wave modulation is proposed in this article to calibrate the phase shift in order to eliminate its effects. Firstly, the impact mechanism of phase shift on WA CVG is analyzed, and phase shift introduces coupling between gyroscope control loops and angular drift. Then, the error model is established, and a self-calibration method based on square wave modulation is proposed. Finally, the self-calibration experiments are carried out. The results show that phase shift can be effectively self-calibrated under various speed conditions. Compensated scale factor nonlinearity decreases by 96.5% and bias decreases 41%, which verifies the effectiveness of the method.