Research on Torpedo SINS/Trajectory Integrated Navigation Method Considering Gravity Disturbance

In order to solve the problem of torpedo positioning error caused by gravity disturbance and improve positioning accuracy, firstly, the spatial characteristics of gravity disturbance are analyzed. Based on the error equation of inertial navigation system, the influence of gravity disturbance on the state of torpedo inertial navigation system is analyzed. Considering the strong coupling relationship between accelerometer bias and gravity disturbance, when they are in the same order of magnitude, the accelerometer bias must be compensated, otherwise new positioning errors will be introduced. Therefore, based on Kalman filter, SINS / Trajectory integrated navigation system is designed to estimate the zero bias of the accelerometer, and the observability of the zero bias of accelerometer in three axes is calculated by using the observability analysis method based on singular value. The maneuver track is designed to improve the zero bias observability and make zero bias converge to the true value quickly. The simulation results show that the positioning accuracy of inertial navigation solution is improved by 24.5% after the gravity disturbance is compensated by the gravity field model, and the positioning accuracy is further improved by 65.0% after the accelerometer bias is estimated by Kalman filter.