Research On The Relationship Between The Received Signal Of The Figure-8 Coil And The Target Position

With the continuous advancement of urban modernization and the development of science,the demand of detecting underground information is becoming stronger and stronger,and the shallow surface electromagnetic detection technology has very broad application prospects.In the fields of urban underground pipeline laying,geological resource exploration,rail transit construction,unexploded ordnance detection,etc.,it is necessary to accurately obtain the position information of the target under the shallow surface.In this dissertation,combined with the transmission characteristics of electromagnetic waves,the working principle of the shallow surface electromagnetic detection system is introduced.According to the figure-8 receiving coil structure detection system developed by Jilin University,the characteristics of receiving and transmitting mode and the loop mode of the receiving coil are analyzed.The mathematical model of the figure-8 coil structure is researched emphatically.The magnetic induction intensity generated by the rectangular transmitting coil is calculated and the characteristic response of the target body is analyzed.Combining the orthogonal dipole model to equivalently analyze the induced field effect of the metal anomaly in the primary field,and calculating the received signal of the figure-8coil.Analyzing the distribution of the primary field at different depths through Matlab simulation,and combining the distribution of the received signal to analyze the characteristics of the one-transmit and five-receive coil structure that can effectively distinguish the target body axis position information.At the same time the efficiency of the detection system is improved.The relationship between the received signal and the position information of the target body's level,depth,and inclination angle is study,and an analysis method for judging the target body position information based on the received signal is proposed.The experiment verified the consistency of the relationship between the eigenvalue signal of the receiving coil and the depth of the target body and the simulation results.The received signals at different depths are compared with the simulation results,and the depth deviation generated at different depths is counted.The depth deviation is less than 4% when the depth is less than 50 cm.The simulation result can effectively judge the position information of the target.The experiment tested the influence of the target body's inclination angle on the received signal,which is more consistent with the distribution law of the simulation results..The peak of the received signal gradually moves to the coil frame as the target body tilt increases,and the amplitude first increases and then decreases.Through the target body position detection experiment,the simulation result is used to make a more accurate judgment on the target body position information,which verifies the accuracy and validity of the coil model.