Strapdown Inertial Navigation System Initial Alignment Based on Modified Process Model

In this paper, the nonlinear initial alignment method for Strapdown inertial navigation system is investigated. As an important part of the nonlinear initial alignment method, the dynamic model based on nonlinear error equations is re-derived with the consideration of the mismatch between the calculated navigation frame and the actual navigation frame. Then, the recursive nonlinear initial alignment procedure based on the modified model under the marine mooring condition is elaborated. The superiority of the proposed method over traditional method in terms of rapidness, accuracy, and consistency is validated through simulated and experimental tests.