SVD-based Adaptive Algorithm For Direct Wave Suppression In Ultrasonic Rail Flaw Detection

As the world's largest high-speed rail country,China's high-speed rail has reached 25,000 kilometers of its operational mileage,ranking first in the world,and it is still maintaining its leading position with an annual growth rate of 4.5%.The construction of high-speed rail as a super-project is a miracle of China's economic development.Its global "China speed" has greatly accelerated China's transportation of goods and personnel.Rails,as the carrying component of railway transportation,directly affect the safety of railway transportation.However,the overload operation has caused a high incidence of rail damage.Therefore,the Ministry of Railways has stipulated that each line must be tested 5 to 10 times a year.With the rapid growth of China's railway mileage,and the construction of high-speed railways and subways in major cities,the accuracy requirements for rail flaw detection are also increasing.On the basis of consulting a large amount of literature,make a summary of the principle,development history and current research status of the ultrasonic rail flaw detection technology.Analyze the advantages of ultrasonic inspection for flaw detection and direct wave interference problems,and make a summary of the research on the direct wave suppression research at home and abroad.Then carried out research on the direct wave suppression algorithm in ultrasonic rail flaw detection,mainly including the following aspects:1.Aiming at the problem of direct wave suppression in ultrasonic rail flaw detection,a direct wave suppression method based on adaptive filtering is proposed: Because it is difficult to obtain the prior knowledge of the direct wave and the reflected signal from the received signal,the transmission channel is unpredictable.Filters with constant parameters cannot achieve the filtering effect,so an adaptive filter that automatically adjusts parameters can be used.2.In ultrasonic rail flaw detection,study the direct wave suppression performance of two adaptive algorithms,least mean square algorithm and recursive least squares algorithm.Through numerical simulation,the recursive least squares algorithm with better performance is selected for this scenes.3.For the reference direct wave signal needed in adaptive filtering,a Hankel matrix is constructed by using single point measurement data,then the singular value decomposition of the matrix is used to denoise,so the reference direct wave signal is extracted.4.Finally,this paper proposes a SVD-based adaptive algorithm for direct wave suppression in ultrasonic rail flaw detection and confirms it with experiments on the self-developed ultrasonic flaw detection platform in laboratory and simulation data.The experimental results verify that the algorithm has good performance on direct wave suppression.