Research On Magnetic Target Location Method Based On Equivalent Magnetic Force

With the development of magnetometry,the physical quantities that can be detected using magnetometers are becoming more and more abundant,including the total geomagnetic field,the magnetic field vector,and the magnetic gradient tensor.The magnetic gradient tensor has a significant advantage over the magnetic scalar and magnetic vector,as it can obtain more adequate information and is less susceptible to geomagnetic fluctuations.The localization of magnetic targets is a hot research topic in the field of magnetometry,which is especially suitable for military and civil applications such as anti-submarine,unexploded ordnance detection,and mining.However,magnetic targets are complex,variable,and unpredictable,and have high requirements for localization methods.In this paper,we propose a method to calculate equivalent magnetic force by combining magnetic field vector and magnetic gradient tensor,which has the characteristics of simple operation,stable numerical calculation process,and high robustness,and can be used for the localization and identification of magnetic targets.According to the motion state of magnetic targets,this paper conducts research in the following two aspects respectively.For dynamic magnetic targets,this paper uses the equivalent magnetic force method to calculate the orientation vector of magnetic targets to achieve the function of location tracking.Firstly,the motion models of four magnetic targets are designed to generate random trajectories under different motion states,and the motion tracking models between detectors and magnetic targets are designed.Then,based on the magnetic field forward modeling,the magnetic field simulation data of the magnetic targets are obtained,and the dynamic magnetic target tracking simulation experiments are carried out to verify the orientation information calculated by the detector by combining it with the location tracking algorithm.The actual detection process is simulated by superimposing noise on the orthorectified magnetic field data and compared with existing localization methods such as the Eulerian deconvolution method,generalized inverse method,and non-inverting Euler method,the mean squared deviation of the three methods is 196.02,193.87,and 10.26 times higher than the equivalent magnetic method under the same noise level of simulation,respectively.Finally,this paper also verifies that the equivalent magnetic localization tracking method has higher stability and robustness through practical experiments.For static magnetic targets,this paper uses the dispersion of the equivalent magnetic force to constrain the localization results based on Normalized Source Strength(NSS).Based on NSS,the data from the detection plane can be used to locate and identify magnetic targets,but the solution results are not stable in the actual detection process.The existing methods use parameter constraints to reject the invalid solutions in the solution results,but they need to constrain multiple solution parameters and the stability of the parameters is poor,which increases the difficulty of the parameter constraint method in the process of static magnetic target localization and identification.In this paper,we use the method of constraining the solution results based on the dispersion value of the equivalent magnetic direction vector and adjust the degree of constraint by changing the scale value of dispersion to improve the localization efficiency of the method.In this paper,the method is validated from simulations and actual experiments,in which the method based on dispersion constraint can improve the reasonable rate of localization by 30% compared with the parameter constraint method,and the high robustness of the equivalent magnetic force method in the process of static magnetic target localization recognition is verified.In this paper,the equivalent magnetic force method is applied to the tracking of dynamic magnetic targets and the identification of static magnetic targets respectively,both of which verified the high robustness of the method and provided a new idea and reference for the localization of magnetic targets.