Research on initial alignment method of vehicle-mounted SINS based on reverse navigation

In order to improve the alignment accuracy and speed of vehicle-mounted SINS, an initial alignment scheme of “inertial solidification alignment + Kalman filter fine alignment based on reverse navigation” is proposed in this paper. Firstly, an inertial solidification alignment algorithm is derived, the initial alignment problem is transformed into Wahba problem, and the optimal attitude matrix at the initial moment is obtained by singular value decomposition algorithm. The inertial solidification alignment algorithm is more concise and intuitive than the traditional alignment algorithm of geocentric inertial coordinate system. Then, we analyzed the effectiveness of rotation modulation technology to improve alignment accuracy theoretically and proved it by simulation. And it is pointed out that the application platform space is limited and the system cost is increased when using this technology. Furthermore, in order to overcome the shortcomings of using rotation modulation technology, a Kalman filter algorithm based on reverse navigation is derived. By reusing the data stored during the inertial solidification alignment, the alignment time is extended equivalently, the initial attitude error is reduced and the attitude calculation accuracy after forward navigation is improved, higher precision alignment is realized. Finally, the effectiveness of the initial alignment scheme is verified by simulation.