Magnetic Object Positioning Based on Second-Order Magnetic Gradient Tensor System

Target positioning by the magnetic tracking system is extremely susceptible to the influence of the geomagnetic field. To accurately locate magnetic objects, we design a second-order magnetic gradient tensor (SMGT) system based on the plane-cross magnetic gradient tensor (MGT) system. With the constraint equation of MGT spatial invariants, the magnetic source position coordinates are solved by the SMGT and Euler deconvolution. The simulation shows when the Gaussian noise variance is less than 3 nT and a magnetic dipole with scalar 6000 Am
²
moment within 10 m distance, the positioning accuracy of the method can be controlled within the range of about 3 m root-mean-square error (RMSE); in actual measurement, after system calibration, the method realized a small magnet (diameter 5 cm, thickness 0.5 cm) positioning where the RMSE is suppressed in 14 cm in a 2.1 m heading-line detection interval.