Contour matching algorithm for passive gravity navigation

A contour matching algorithm for gravity aided inertial navigation system (GAINS) is presented based on the optimization of merit function. According to the navigation information provided by inertial navigation system (INS) and gravity field measurement, the algorithm makes full use of the characteristics that INS has high precision during a short period, and determines a matched path by searching, tracking and making a decision on a priori gravity map to realize precise navigation and localization with the aid of gravity. The simulation results based on a gravity anomaly map of an actual sea area prove that the matched error of the proposed algorithm under operating sea condition can be limited in less than one gravity map grid and is not influenced by the positional error of INS; the proposed method overcomes the uselessness of other matching algorithms under the circumstance of large INS positional error.