Research on Initial Alignment for Large Azimuth Misalignment Angle with Sage_Husa Adaptive Filtering

The azimuth was often a large angle because navigation accuracy of fiber-optic inertial navigation system is not high, and the filtering equations of initial alignment are non-linear. In order to improve the initial alignment accuracy of nonlinear models, a improved Sage_Husa adaptive Kalman filtering method is put forward, and applied to initial alignment of fiber-optic inertial navigation system. This paper establishes initial alignment nonlinear model of large azimuth misalignment angle, contributes the system noise statistics estimators, and uses improved Sage_Husa adaptive Kalman filtering to simulate for nonlinear error equations. The simulation results show that the improved Sage_Husa adaptive Kalman filtering could deal with nonlinear problems, improve the accuracy of initial alignment. Azimuth misalignment angle error can converge 13.353', better than 48.539' of EKF.