Portable Automatic Ultrasonic Nondestructive Testing Precision Positioning Device System Design

With the rapid development of high-speed railways,the orbital loads increase simultaneously.It is directly related to the safety of the trains that the rails are used to carry and guide the trains are in good health.Therefore,it is of practical significance to detect the damage of rails in service.Based on the principle of ultrasonic pulse reflection detection,this paper studies the in-service rail damage precise positioning system.Firstly,the whole system scheme and damage identification algorithm are designed.In order to achieve the goal of higher flaw detection speed and flaw detection accuracy of the flaw detection system,this paper proposes a system scheme for separation of detection and observation,and implements wireless communication between detection and observation through Bluetooth.The architecture of ARM + FPGA are used as the center of calculation and control of the system,and the data transmission between the two is realized through the FSMC interface to complete the real-time processing of the dual-rail echo signals.Based on the similar characteristics of ultrasonic echo signals,this paper The damage identification algorithm was determined by adopting no-time difference cross-corre lation and sliding window cross-correlation algorithm.Based on the characteristics of frequency and envelope of ultrasonic echo defect signal,an ultrasonic echo defect model was established,and the feasibility of the algorithm was verified by MATLAB.The performance of the algorithm was verified by simulation when adding±5dB SNR noise.Based on this,a multi-platform hierarchical algorithm damage identification solution is proposed,and an algorithm state machine is used to implement the solution.In addition,the main factors affccting the performance of the probing system are analyzed,the form of the ultrasonic excitation signal is determined,and the key parameters of the ultrasonic excitation circuit are determined through experiments.The FIR filter is used to filter the echo signal.The time-differenced cross-correlation algorithm is implemented on the FPGA,and the optimized resource consumption of the algorithm is 36%when it is implemented directly through the time-division multiplexing of the equivalent transformation and the arithmetic module.This article completes the system's hardware and software design,the SolidWorks 3D modeling of the flaw detection device,and generate specific requirements for processing the model;complete FPGA data acquisition and control circuit,ultrasonic transmitter and receiver circuit and FIR filter design based on distributed algorithms In the ARM platform to complete the implementation of the algorithm state machine,multi-probe rotation incentive mechanism,rail adaptive module and handheld device interactive interface design.Through the establishment of a debugging platform in the laboratory,the hardware and software debugging of the flaw detection system was completed.While verifying the functional correctness of the various modules of the system,the communication efficiency between the FSMC and the SPI was compared.The results show that the FSMC is approximately 27 times that of the SPI,which greatly improves the System performance.At the same time,the time-consuming introduction of man-made damage on the rails and the simulation test in the standard test block CSK-IA show that the flaw detection system can correctly identify nuclear damage,?1.5mm hole damage,and 1mm cracks.Finally,the actual test at the scene,the results show that the flaw detection device can correctly identify the rail joint damage,which provides a useful exploration for rail flaw detection in service in China.