Design And Implementation Of Electromagnetic Nondestructive Testing System Based On FPGA

In recent years, electromagnetic nondestructive testing on the quality of steel material has been studied and acquired a great deal of achievements for its merits of nondestructive, convenient and fast. However there are many problems in the testing of hardness and cracks, and mess problem of work pieces. For example, the effect of traditional nondestructive testing for the hardness of steel pieces is not very ideal.To settle the above problems, this paper attempts to apply advanced SOPC solution to the electromagnetic nondestructive testing system. The SOPC solution integrates all components the system needs into a piece of programmable logic device to construct a system on programmable chip.This paper has discussed the theory of electromagnet nondestructive testing device based on FPGA in detail, and the overall design has been given. This paper introduces the whole design procedure of analogue system, system configuration and software system. The paper adopts Verilog HDL to achieve excitation signal generator and high-speed data acquisition by means of the features of custom peripheral of Quartus II and arbitration mechanism of Avalon bus. The function of excitation signal generator and high-speed data acquisition are implemented in the same chip, which improves the accuracy of signal and signal processing. Due to sensitive reactions to multiple parameters, the testing instrument must be able to restrain influence of multiple disturbances. The design adopts FIR digital filter and Correlation method to extract amplitude and phase of the signal from multiple disturbances. And then uses Nios II C2H to accelaerate the filter, which improves the speed of signal processing. Last, the paper uses the least-squares method to access to the regression equation. The result of quality inspection for hardness of bearing steel, using the system, was satisfactory.The result indicated that applying SOPC technology to electromagnetic nondestructive testing system can improve the speed and accuracy of testing. And the scale, reliability, index of performance, development cost, product maintenance and hardware upgrade of the design has achieved optimization.