Observability Analysis of SINS/GPS during In-Motion Alignment Using Singular Value Decomposition

The in-motion alignment of a SINS/GPS integrated system uses the GPS velocity and position as observations, hence the SINS position and velocity errors are instantaneously observable. However the attitude error is not directly observable, it is important to find a way to improve the observability of attitude error because the degree-of-observability of the attitude error affects the accuracy of alignment. In this paper, the singular value decomposition (SVD) method is used to analyze the degree-of-observability of SINS/GPS during in-motion alignment. Simulations involving nine typical maneuvers indicate that both the yaw-axis rotation and the accelerated motion can improve the degree-of-observability of attitude error. Of the nine types of maneuvers, the triaxial rotation with acceleration is the most effective maneuver for improving the degree-of-observability of a SINS/GPS integrated system.