| With the development of the Internet of things, item identification technology, as the key component of it has observed widely concern. Recently, barcode recognition, RFID identification and metal tag identification technologies con sist the mainstream techs. The system of metal tag is not only able to solve the limits of identification, but also have the advantages of fast testing, integration of items and higher accuracy. In this paper, I mainly studied the identification of metal t ag, and its core technology is eddy current nondestructive testing technology. Using the electromagnetism technology, I’ve done theory analysis, modeling, simulation, known label information to analyze the changing situations of incremental impedance in se nsing coil.This artical summarizes the classifications and operating principles of recent identification technologies and eddy current nondestructive testing technology. On this basis, I studied the time-harmonic field of Maxwell equations to induce the vector magnetic potential, which is for the description of de finite solution problems about eddy current field. Through deriving analysis, I’ve got that the distribution of the electric field is decided by magnetic potential vector. Then, I build the Eddy current testing model. With the analysis of defects of eddy current testing, I found that current field has two parts. One part of it has only calculated, in the non-defect condition, the extrinsic motivation of eddy current field. The other part is that without the extrinsic motivation, how the defects influence the current field. During the calculation, I brought the triple integral equation and the dyadic green ’s function,which I optimize the parameter to decrease the complexity and time with ensuring of accuracy. Thirdly, I saw the tag as ideal crack, equalizing the defect parts to dipole layer and then finding the numerical solution of the integral equation. I calculated the detecting coil impedance in the incremental changes. Through MATLAB, changing the frequencies, horizontal movement, changing height to observe the changes of incremental impedance, which has guiding significance for engineering practice. |
