A Mismatch Diagnostic Method for TERCOM-Based Underwater Gravity-Aided Navigation

Gravity matching algorithm is the pivotal technique in gravity-aided navigation, which is the main method in the application of underwater autonomous vehicle. TERCOM algorithm is one of the classical matching algorithms in this research field. Due to the characteristic of inertial navigation system (INS) location error, an affine or a rigid transformation relationship between actual vehicle trajectory and INS-indicated trajectory is assumed to be existed. In order to improve the accuracy of TERCOM algorithm, a mismatch diagnostic method based on the restricted spatial order constraints (RSOC) algorithm from image registration is assisted. RSOC strategy integrates spatial order constraints and decision criteria restrictions to screen outliers in a matched sequence. It is obtained that the mismatch diagnostic method can select the mismatched points accurately. Therefore, the matching algorithm with mismatch detection mechanism has better performance. The reliability and accuracy of the method are verified via simulation tests.