Experimental Study On Passive Weak Magnetic Detection Technology Of Metal Object

In recent years,the number of sudden violent incidents which endangered public security in schools,hospitals,railway stations and other public gathering places has shown an upward trend,and the application of metal detection in the field of security has been widely concerned.The existing metal detection technology have some limitations in the detection process,such as a certain degree of ionizing radiation will be produced in the detection process,the contour display of personal body will violate personal privacy,close(personal)security detection is inconvenient and so on,which result in its limited application in the aspect of human security inspection.In this paper,based on the physical phenomena that metal objects will generate magnetic anomaly field under the action of geomagnetic field,a passive weak magnetic detection technology of metal objects was proposed to realize the efficiency and safety of human security inspection.Firstly,this paper introduced the basic principle of passive weak magnetic detecting technology for mental objects,and analyzed the feasibility of the passive weak magnetic detection for metal detection by theory.Secondly,based on the analysis of the existing magnetic anomaly field detection technology,two kinds of detection devices with the cross-structure and the double-row array structure were designed by using the magnetic flux sensor.The advantages and disadvantages of the two structures were analyzed and compared through tests,and the array structure was found to have the advantages of highlighting the magnetic anomaly field and reducing the number of sensors,so the weak magnetic detection for metal objects was determined to be done by the double-row array detector.Third,the magnetic field values of sphere and cuboid were calculated which are two kinds of typical regular body,and the magnetic field distribution characteristics of the metal objects whose relative actual detection distance are point dipole model and plate body model were analyzed based on that.Fourth,the placement method,length dimension and detection distance test of metal objects were carried out by selecting thin iron as the object of study.On the basis of the magnetic field calculation of regular body and the analysis of test results,the experimental rules were summarized and the research on the algorithm of passive weak magnetic detection technology for metal objects was studied.Finally,a set of software of passive weakmagnetic detection for metal objects was designed by using the c# programming language,which can accomplish the functions that real-time imaging of magnetic anomaly for metal objects,camera monitoring,alarming and so on.The software was used to carry out the metal detection experiments in the laboratory.The test results show that the metal passive weak magnetic detection technology can identify metal objects and the software has a certain practicality.The passive magnetic field detection technology provides a new idea and new method for metal detection in the field of security,which lays the foundation for further application to other metal detection areas such as enterprise management.