A method for improving calibration accuracy of the inertial navigation system based on gravity disturbance compensation

Accurate calibration of the inertial navigation system (INS) is essential for enhancing its performance. However, gravity disturbance significantly impacts the calibration accuracy of the INS, directly reducing the navigation performance of the high-precision INS. This paper investigates a method for further improving the calibration accuracy of the INS through compensating gravity disturbance. A full-parameter error model incorporating gravity disturbance for INS is established, the impact of gravity disturbance on INS calibration accuracy is analyzed, and gravity disturbance compensation method is proposed. Finally, the 19-position calibration experiment, the static-based navigation experiment and vehicle experiment are carried out to validate the effectiveness of the proposed method. Experiment results indicate that a 20 '' meridian vertical deviation introduces a calibration error of 0.001 degrees h-1 in the X-axis and Y-axis gyro drift, a 10 mGal gravity anomaly results in a 10 ppm calibration error in the three-axis accelerometer scale factor, while the impact of the prime vertical deviation on the INS calibration accuracy can be ignored. After compensating gravity disturbance during the INS calibration process, the 60 min static navigation accuracy improved from RMS (root mean square) 332.81 m to 272.80 m and the 70 min dynamic navigation accuracy improved from RMS 1371.8 m to 1067.2 m.