Research On Magnetic Target Detection Method Based On Magnetic Anomaly

The existence of geomagnetic field is one of the necessary conditions for the detection of magnetic anomalies.The interaction between geomagnetic field and ferromagnetic objects leads to the occurrence of magnetic anomalies.Magnetic Anomaly Detection(MAD)technology is precisely based on magnetic anomalies to achieve the detection and positioning of ferromagnetic objects.Magnetic anomaly detection technology is different from radar,sonar,laser and other active detection methods.It is a non-contact passive detection method that relies on basic physical phenomena.With its unique advantages,it is widely used in space exploration,geological resource exploration,detection of unexploded ordnance(UXO),submarine and other concealed magnetic targets,and has important civil and military value.This article mainly studies the detection and localization methods of ferromagnetic targets,and the specific research content includes the following aspects:This article first introduces the basic principles of magnetic anomaly detection based on the characteristics of the geomagnetic field,the magnetization process of ferromagnets,and the generation principle of magnetic anomalies.The submarine target was modeled using finite element simulation models,hollow rotating ellipsoid models,and magnetic dipole models,with a focus on analyzing the spatial characteristics of the submarine target’s magnetic field and the applicability of the magnetic dipole model.In the detection of magnetic targets,the application conditions of the standard orthogonal basis function(OBF)decomposition algorithm have been broadened from three aspects.In view of the large limitations of OBF detection model,the motion conditions between the target and the magnetic measurement equipment are broadened to the conditions of simultaneous motion in different directions at different speeds.Aiming at the problem that the closest proximity approach(CPA)distance between the target and the moving track is unknown,an improved multi-channel estimation method based on the gradient rising method is proposed.Simulation results show that this method can estimate CPA distance efficiently and accurately.To solve the problem of poor detection performance of OBF decomposition algorithm in non-Gaussian environment,an improved OBF decomposition algorithm based on whitening filter is proposed according to the characteristics of geomagnetic noise,which extends the OBF decomposition algorithm to non-Gaussian white noise.Simulation and field test results show that the improved OBF decomposition detection algorithm also has a good detection effect under non-Gaussian white noise conditions.In terms of magnetic target localization,the Euler deconvolution localization method is extended to the category of multi magnetic target localization,and an improved discrete Euler solution quality control method is proposed by combining the DBSCAN density clustering algorithm,which solves the problems of poor resolution and low positioning accuracy in multi magnetic target localization.The effects of detection height,measurement point spacing,magnetic target spacing,and depth difference on the positioning performance of multiple magnetic target positioning methods were analyzed through simulation.The simulation and actual data processing results show that the improved Euler deconvolution localization method proposed in this paper can accurately determine the number and spatial position of magnetic targets in the detection area.