Study On Magnetic Object Localization Method Based On Magnetic Dipole Model

The method of magnetic object localization is that dealing with the data of magnetic from the magnetic measurement system and obtaining the position of the magnetic object. It will have an increasingly application in resource exploration and military affairs. In this subject, the measurement principle of a cross structure of plane magnetic gradient measurement system which is composed of four sensors is introduced, and the measurement error is also eliminated. On the condition of magnetic dipole model, some different localization algorithms are proposed, as well as relevant analytical study, analog study and experimental study are made.Firstly, in order to overcome the infection of different induced magnetic field component by carrier poses, the localization algorithms based on magnetic module are introduced, one of them is only based on the total amount of magnetic field and especial measurement locus, the other is locating effectively by multi-modules of magnetic field. The former based on the general carrier induced magnetic field model and the correlation of two sensors output, a difference compensation formula for different carrier induced magnetic field is deduced. The compensating result is a curve showing the change of the total amount of magnetic anomaly field at a measurement locus. Then the magnetic object position can be obtained by curves of different measurement locus. The simulation results demonstrate that this localization is feasible theoretically. The latter is a localization method of a magnetic dipole, which obtains the range of the magnetic dipole by using it’s magnetic anomaly intensity, total gradient module and magnetic gradient tensor, and gets the coordinate from multi-ranges and multi-coordinates of array’s position. The factors influencing the localization error are analyzed in theory, the simulation and experiment results demonstrate that the main factors influencing the ranging and locating error are accuracy of the magnetic detector, baseline interval and the range. Comparing with the direct inversion algorithm, the proposed method is less sensitive to noise and direction of the magnetic dipole moments, which is more significant in application.Secondly, in order to overcome the difficult problem of measuring the magnetic anomaly field component and avoid the infection of geomagnetic fi eld, the localization method to determine the source location from the eigenvectors and eigenvalues of the tensor is proposed, which need magnetic gradient tensor as main measurement data, and the coordinates of array’s position as assistant measurement data. Four possible solutions can be get from tensor, then unique direction and location can be sure if we know the assistant measurement data, too. The main factors influencing the directing and locating error are analyzed theoretically. The simulation and experiment results demonstrate that this localization is feasible, but localization error is not a little, the more studies are demand.On the condition of magnetic dipole model, some different localization algorithms based on different measurement data are proposed in this subject. Although each one aims at overcoming the difficult problem in the magnetic object localization technology, which has its inherent defect, therefore which one should be chosen depends on real instance in application, it also point out what we should do in the future.