Calibration of Magnetometer Arrays in Magnetic Field Gradients

The calibration of vector magnetometer arrays plays an important role in the detection of ferromagnetic targets. Traditional calibration methods assume that the magnetic environment is uniform and stable, which often is not the case. We describe a calibration method for nonuniform environments based on the redundancy of magnetic flux density tensor elements B-xy and B-yx and the fact that the tensor rotational invariant remains constant at one point, independent of posture. The compensation model focuses on the gradient field, which largely eliminates geomagnetic fluctuations over time. The calibration procedure is completed at one point, which avoids problems with spatial nonuniformity of the magnetic field. Simulations confirm that the proposed calibration method provides an effective and more accurate compensation performance in inhomogeneous magnetic environments.