In-Motion Coarse Alignment Method for SINS/GPS Using Position Loci

Misalignment angle is an important error in the integration of the strapdown inertial navigation system (SINS) and the global positioning system (GPS). Currently, the popular methods for SINS/GPS integrated system are based on the ground velocity. There are two major defects: 1) not all GPS receivers provide the velocity outputs and 2) the contained outliers in the velocity will degrade the performance of the alignment methods. In this paper, an in-motion coarse alignment method for SINS/GPS integrated system using position loci is proposed. First, the observation vector for the in-motion coarse alignment with the position loci is derived. Different from the current popular methods, the constructed observation vector is just relative with the GPS positioning information, which can be obtained from any GPS receiver directly. Thus, the applicable range of the in-motion coarse alignment method is extended. Second, based on the advantages of the position loci, the proposed method can suppress the interferences of the outliers, which are contained in the GPS positioning outputs. Finally, the simulation and field tests are designed to verify the performance of the proposed method. The test results show that the proposed method is more robust than the current popular methods.