An integrated calibration method for the cross-shaped magnetic gradiometer

The measurement accuracy of a magnetic gradiometer relies on magnetometer consistency, measurement accuracy, and assembly technology. The traditional methods calibrate measurement error, misalignment error, and the interference magnetic field independently. However, after a long time of work, the calibration parameters will inevitably change. Furthermore, it will waste a lot of manpower and material resources if the magnetic gradiometer is disassembled and calibrated step by step. Given the above problems, a novel attitude-independent calibration algorithm using a limited number of measurement points is proposed, which can effectively overcome the measurement distortion of the magnetic gradiometer and does not rely on a reference magnetometer. For the cross-shaped magnetic gradiometer, the simulation results show that the error after integrated calibration is reduced to less than 8% of the error before calibration. The test results suggest that the magnetic gradient results before calibration are even up to 1.5 µT/m, whereas the magnetic gradient results after the integrated calibration are less than 100 nT/m.