Identification and Calibration of the Detection Signal Distortion in Whole Angle Mode Hemispherical Resonator Gyro

The hemispherical resonator gyroscope (HRG) senses the position of standing wave by detecting the capacitive gap between the hemispherical shell resonator (HSR) and electrodes. However, the variable gap distance, resonator deformation, and fringe effect formed with the divergent electric field can distort the detection signal, resulting in the angular rate error of the whole angle (WA) mode HRG. Aiming at this problem, the analysis of the distortions in capacitive detection is conducted theoretically. Then, mathematical models are established to describe the angular rate error and verified by experiments. The experimental results show that the angular rate error introduced by the detection signal distortion is associated with the eighth harmonic of the standing wave azimuth. Lastly, the identification and calibration method based on the recursive least square (RLS) algorithm is proposed, which can reduce the angular rate error by 25 times, and the angular rate error is suppressed from 0.0381°/s to 0.0015°/s after calibration.