Research On Near Field Ultrasonic Source Localization Technology Based On Single-Launch-Multiple-Receive Array

With the continuous development of modern industrial inspection, medical diagnostics,transport and ship inspection, mineral exploration and other fields have put forward higherrequirements to non-destructive testing technology. As the most commonly usednon-destructive testing technique method, ultrasonic testing technology has been widelyconcerned. The research of ultrasonic testing technology and the development of ultrasonictesting equipment is regarded as one of the important direction of technology development bydomestic and foreign. With the development of digital signal processing technology, computertechnology, electronic technology and precision equipment manufacturing technology,modern ultrasonic non-destructive testing technology gradually develop into greater accuracy,higher testing speed, higher accuracy and better portability.Because crossing and deepening with digital signal processing technology is one of themain development directions of ultrasonic testing, this paper proposes a new method ofultrasonic localization by modifying the passive near-field source array signal processingalgorithm. This method can realize ‘single-launch-multiple-receive’ to locate the defectpoint(reflection point) in the rail, which avoids ‘multiple-launch-multiple-receive’ model’spoint scanning the tested object, like ultrasonic phased array method, etc. The paper’s mainresearch contents include:In the second chapter, we introduce the basic theory of ultrasonic non-destructive testingand the traditional ultrasonic testing method. In the third chapter, we introduce‘multiple-launch-multiple-receive’ model and analyze its advantages and disadvantages, bythe example of the ultrasonic phased array. In the fourth chapter, we make use of the arraysignal processing model and set up the ‘single-launch-multiple-receive’ receiving probe arraymodel. Then we respectively carry out the simulation analysis of the receiving modelperformance based on ESPRIT algorithm and MUSIC algorithm and make comparison andanalysis of the some parameters’ influence to the probe array’s estimation performance, suchlike element spacing, element number, signal-to-noise ratio, snapshots and so on. In the fifthchapter of the paper, combining with the foreshadowing of previous chapters, we propose a‘single-launch-multiple-receive’ localization algorithm which is applied to rail flaw detection. With the algorithm simulation verification, the simulation verifies the availability andfeasibility of this algorithm. Then we comparatively analyze the advantages anddisadvantages of the algorithm, and the improvement projects on the shortcomings arediscussed.Taken together, the innovation points of this paper involve:1. Combining the array signal processing method with the method of ultrasonic testing,we modify the two-dimensional passive testing method of signal processing, and propose‘single-launch-multiple-receive’ localization algorithm which is applied to rail flaw detectionand realize the purpose to measure the distance of the defect point to array element.2. With the optimization algorithm, this paper reasonably estimates multiple receiveddistance of the defect point to the array element to get the high-precision defect pointcoordinates. This method fulfills the purpose of detecting defect point coordinate with‘single-launch-multiple-receive’. And setting up reasonable search threshold reduces theamount of calculation and improves the operation speed of the algorithm.