Development Of Ultrasonic Inspection Decice Hardware Systems Based On FPGA

At present, using the ultrasonic to detect a dangerous fatigue cracks and flaws in hollow axle of the key components of high speed train bogie is an important and non-destructive testing method to ensure the safety of high-speed train. In recent years, the rapid development of the field programmable gate array (FPGA) and high speed digital signal processing technology provides the technical support for the fast detection and automation of digital ultrasonic testing system. This thesis studies key technologies for ultrasonic inspection device based on FPGA and develops a multiple high-speed railway hollow axle ultrasonic flaw detection hardware system. Main studies are as follows:(1) This paper proposes and realizes an ultrasonic flaw detector hardware circuit design with the combination of a high speed digital signal processing system based on FPGA and PowerPC platform, and it also improves the speed of the peripheral high-speed Ethernet interface with real-time display of inspection results.(2) In the aspects of miniaturization and low-power consumption, when choosing chip and design, the labeling packaging and high integration of IC chips is adopted. The circuit designs of power supply, the probe trigger, echo signal acquisitiona and high-speed A/D sampling and so on are peoposed and realized.(3) This paper presents the research principle of key technology for ultrasonic inspection decive, which could solve the practical problems of in the high-speed sampling data flow transmission and real-time processing at speed of80MHz-100MHz, and realize the simulation design of FIR digital filter on multiple platforms. Through VHDL programming, the simulation design of the digital envelope detection technology, non-uniform data real-time compression and ping-pong storage technology are also achieved.(4) In the host computer of UT components debugging, it implements debugging the key technology based on FPGA on the basis of modules and functions. In the host computer for ultrasonic detection system, implements type A, type B, type C real-time display of the ultrasonic testing signal.Compared with the traditional analog ultrasonic flaw detector, several advantage are as follows:automated testing is realized under the control of the host computer; using the parallelism of high speed digital signal processing of FPGA and the real-time efficient multitasking capability of the VxWorks operating system running in PowerPC platform, the precision is improved and the multi-channel parallel processing and real-time display are achieved; according to the attenuation of ultrasonic wave propagation in the medium, the paper is designed and impled as the time gain compensation circuit; the more frontier multiple platforms simulation technology is adopted and so on.Now, the first prototype of ultrasonic flaw detection system has been designed successfully and been connected to the host computer for testing and debugging. The test results can satisfy the requirements of the actual testing, and achieve the requirements of the performance index of system design.