Asphericity Errors Correction of Magnetic Gradient Tensor Invariants Method for Magnetic Dipole Localization

The localization method of a magnetic dipole based on the magnetic gradient tensor invariants is the Scalar Triangulation And Ranging method (STAR), which is used to solve the multiple solutions problem for the real-time localization of magnetic dipole by the spatial geometric relationship of the tensor rotation invariants. The method is not involved in the measurement of the magnetic field vector greatly affected by the geomagnetic field. Simultaneously, it is very suitable for underground and underwater exploration such as the exploration of unexploded ordnance. But, it has asphericity errors, which can make the azimuth errors of up to 5°. In addition, it is tightly coupled with the magnetic properties of the target. Thus, we proposed an iterative method to correct the asphericity errors. In this method, beginning with the results of the STAR method, the defective parameters obtained by the sensor structure were used to rapidly correct the localization errors and enhance the properties of real-time localization. The relative errors of the components of bearing vector were reduced by a factor of 7, and they were not influenced by the magnetic properties of the target.