Ultrasonic Guided Wave Break Detection Algorithm Design And Hardware Implementation

The high-speed rail is one of China's four new inventions,it plays a decisive role in modern transportation.Excessive use of tracks is prone to damage or even broken rails,which Seriously affect the transport and even threaten people's lives..Therefore,It is urgent to study the broken track detection algorithm.This paper mainly focuses on the detection algorithm of ultrasonic guided wave broken track,including signal filtering,broken track positioning and judgment of broken track size.Because the ultrasonic waveguide signal is susceptible to noise,this paper uses Empirical Mode Decomposition algorithm and Ensemble Empirical Mode Decomposition algorithm to denoise the signal.During the simulation,it is found that EMD has the end-point effect and mode aliasing,and the EEMD calculation is more complicated.Based on the above situation,this paper proposes an modified EMD method.Compared with EMD and EEMD algorithms,the modified EMD method reduces the number of iterations,suppresses modal aliasing and end-point effects to some extent;signal-noise ratio increased by 6%-11%,mean square error decreased by 8%-13%,and the amplitude increased by 2%-10%.In the signal processing of ultrasonic guided wave,the modified EMD algorithm has the best performance and denoising effect.In the calculation of the broken track,the location of the broken rail is determined by the echo method and the envelope method is used to obtain the echo time of the different positions.When the distance of the broken rail is within 100 meters,the error of broken rail position is lm;when the height of the square steel is 20 mm,the maximum error of the damage size algorithm is 4.46%.In this paper,MATLAB is used for signal modeling and simulation in different noise environments.The actual ultrasonic waveguide signal is used to verify on FPGA.The functional simulation of each module was carried out with ModelSim,and the overall verification was carried out on the development board of DE2-115.The results show that compared with software,the modified EMD method can effectively achieve signal filtering;the error of the off-track positioning algorithm is small,has certain application value.