High Speed Online Electromagnetic Rail Defect Inspection Based on FPGA Parallel Processing System

With the increasing of operation speed and decreasing of interval time of train, high speed railway defect inspection method is required for rail transportation safety. In this paper, method of online electromagnetic rail defect inspection based on FPGA is proposed. This method, Use voltage demodulation algorithm to demodulate the information of amplitude of electromagnetic induction signal, and the results of demodulation are transmitted to host computer for storage and display through Ethernet. All algorithm, including generation of sinusoidal excitation signal, demodulation of amplitude, drive of Ethernet, et al, are implemented by using Field Programmable Gate Array (FPGA). Concept of pipeline and parallel are used when implementing the design, so that the efficiency of calculation is increased to fit the requirements of high speed online railway defect inspection. A real experiment system has been developed to simulate rail defect inspection with high speed condition. For this experimental system, a solid circular steel wheel with crack is used as rail sample and fast rotation of wheel is performed to simulate high speed operating condition. For experiment part, the surface speed of circular wheel is set as 20 km/h, 60 km/h, 120 km/h, 180 km/h, 240 km/h separately. When a certain surface speed option is selected, frequency of sample clock and system clock are both set at 20.48 MHz, 81.92 MHz and 122.88 MHz respectively to signal sampling and data processing for data analysis.