Research on initial alignment of SINS on swaying base through velocity measurement in different coordinates

Two alignment models are proposed to solve the adverse effect of lever arm on initial alignment of strapdown inertial navigation system (SINS) on a swaying base. In the proposed method, the difference between SINS output velocity and lever arm velocity is taken as a measurement and two measurement equations are established separately for navigation frame and body frame. The characteristics of the two alignment models are analyzed. It is demonstrated that the alignment model in navigation frame is only suitable for the case of having lever arm length with a certain precision. On this basis, a filtering method for feedback correction of filter parameters is presented to improve the adaptability of the alignment mo-dels and the alignment accuracy. The simulation results show that the two alignment models are available, and the filtering method is effective for feedback correction of filter parameters.