Optimal arranging and calibrating method for 3D Helmholtz coil magnetic field

Abstract

The invention provides an optimal arranging and calibrating method for a 3D Helmholtz coil magnetic field. The method comprises steps of establishing a differential linear equation group between triaxial magnetometer output and a to-be-tested magnetic field; adopting a crowd searching algorithm and using a condition number of a coefficient matrix as an optimization objective function; generating optimal magnetic field arrangement values in sequence, after stabilization, recording each triaxial magnetometer output of three matrixes, performing subtraction on the triaxial magnetometer output andoutput of a coil without power so as to establish a differential equation group, and obtaining an axial scale factor and an inter-axis coupling coefficient of the triaxial magnetometer; and rotatingan array, recording output of each triaxial magnetometer during two times of rotation, and resolving a mean value of the two times of output, so as to obtain zero offset of each triaxial magnetometer.The method not only can calibrate the axial scale factor, inter-axis coupling coefficient and zero offset of an inter-axis strong coupling triaxial magnetometer array, but also uses a simple, rapid algorithm, has high calibration precision, high efficiency and simple flow, avoids full-attitude spatial rotation of the array, and eliminates impact of zero offset and a constant background magnetic field.

Description

technical field [0001] The invention belongs to the technical field of three-axis magnetometer array calibration, and in particular relates to a three-dimensional Helmholtz coil magnetic field optimal arrangement calibration method. Background technique [0002] Scalar magnetic sensors used for total field and total field gradient measurements include optical pump magnetometers, proton magnetometers, atomic magnetometers, etc., but these magnetometers are large in size, high in power consumption, and high in price, making it difficult to integrate them into an array on a large scale. The three-axis magnetometer array composed of multiple three-axis magnetometers can measure more magnetic field physical quantities and their spatial multi-point distribution, which is helpful for magnetic characteristic analysis and measurement data interpretation of magnetic bodies, and is also a One of the ways to achieve single-measurement positioning. Three-axis magnetometers such as tunne...

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Problems solved by technology

However, these estimation methods tend to fall into local extreme values ​​for the estimation of the measurement coefficients of the three-axis magnetometer with large inter-axis coupling, which affects the calibration accuracy; the geomagnetic field during calibration is a DC constant magnetic field, and the geomagnetic field calibration method is also impossible. The transfer function of the three-axis magnetometer array is calibrated, so it is necessary to use the artificial magnetic field calibration method to calibrate the transfer function of the three-axis magnetometer array

The artificial magnetic field calibration method mostly uses three-dimensional Helmholtz coils for calibration, but the existing literature seldom clearly describes its calibration theory and experiments, and only gives a rough calibration idea sporadically: first, by generating a certain space The uniform magnetic field in the interior cancels the background magnetic field to calibrate the zero bias, and then changes the three-dimensional Helmholtz coil current to generate different coil magnetic fields to calibrate other coefficients; the accuracy of this calibration method greatly depends on the effect of the three-dimensional Helmholtz coil magnetic field on the background The offset degree of the magnetic field, a large residual zero magnetic field will cause a large calibration error of the zero bias of the three-axis magnetometer, and this calibration error will affect the calibration accuracy of other coefficients through the next calibration process

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