SINS/GNSS-Integrated Navigation Based on Group Affine SINS Mechanization in Local-Level Frame

In this article, a group affine strapdown inertial navigation system (SINS) mechanization in local-level frame is investigated for SINS and global navigation satellite system (GNSS) integrated navigation. Traditionally, the SINS mechanization in local-level frame is strong coupling and, therefore, is not group affine. In order to make it group affine, two main procedures are presented. One is making use of damping calculation for SINS, that is, the Coriolis and centrifugal force are ingeniously calculated outside the SINS calculation and filtering recursion using known velocity and position information provided by GNSS. The other is introducing an auxiliary velocity. Then, the trajectory-independent left-invariant error state-space model is derived corresponding to the group affine model. The derived group affine model and its corresponding error state-space model can be used in the SINS/GNSS indirect integration. Simulations and field tests are conducted to evaluate the actual performance of the investigated method. The results show that the proposed method has a much superior performance for SINS/GNSS with large initial attitude error. In contrast, the proposed method has a similar performance with existing state-of-the-art-integrated navigation method when the initial attitude error is small.