Geomagnetic contour matching algorithm based on iterative method

A novel geomagnetic contour matching algorithm based on iterative method is proposed for inertial/geomagnetic integrated navigation systems, which can correct the initial position and heading errors of INS (Inertial Navigation Systems), and lead to high real-time performance. First, the correlation constraint of the matching track and geomagnetic characteristic value is built according to MSD (Mean Square Deviation) criterion. By introducing the parameterized model of the matching track and neglecting the higher-order expanded terms of the first order Taylor expansion, the correlation constraint is translated into a mathematical expression of the displacement and initial heading error. Then the geomagnetic matching problem is converted to the solutions of nonlinear equations according to the correlation criterion. Newton iteration is applied to implement the geomagnetic matching algorithm. Simulation results indicate that the matching error of the contour matching algorithm based on iterative method is decreased to 18.2% compared to conventional contour matching method, and is decreased to 7.8% compared to ICCP (Iterated Closest Contour Point) matching method. Meanwhile, the time consumed in the proposed algorithm is only 5 ms, meeting the real-time requirement.