Research On Digital Ultrasonic Flaw Detection System Based-on DSP And CPLD

With the comprehensive national strength, more and more people are concerned about safety issues in the rapid development of industry, microelectronics and software. NDT technology has been rapid development in order to not destroy the structure of the product itself while testing the quality of the products. Ultrasonic flaw detector is a product of NDT technological development, mainly used to detect workpiece quality.In this paper, the switch contacts in the switching device is widely used as a test workpiece. It is usually need to be defect detection for the output products because this contact impact on the quality of electrical switches directly. The paper discussed the hardware circuit and software design of ultrasonic flaw detector data acquisition system. The system artifacts emit ultrasonic waves to workpiece, and then acquire the reflected ultrasonic echo signal from workpiece and send to the PC. If the workpiece is defective (weld, stoma, misfire, etc.), then the received echo signal includes flaw echo, echo signal is then further processed to obtain defect detailed information. Therefore, ultrasonic flaw detector design is the key to complete the acquisition of the flaw echo signals without distortion. So, this thesis combined pulse echo method in ultrasonic nondestructive testing is proposed data acquisition system based on DSP and CPLD hardware circuit and software design in a ultrasonic flaw detector, including traditional ultrasonic transmitter circuit constant excitation voltage trigger pulse frequency is fixed shortcomings, designed excitation voltage adjustable trigger pulse frequency controlled ultrasonic transmitter circuit; for ultrasonic echo signal voltage is too small for an issue high magnification designed programmable gain amplifier; for ultrasonic echo signal mixed with a lot of noise, a fully differential interference circuit is designed; for high frequency ultrasonic signal acquisition was designed to AD9288 as the core of high-speed data acquisition circuit, USB2.0 data transmission circuits and other hardware circuit module, and wrote related software, and finally, PCB design and soldered components is finished. Finally, the project finished hardware and software debugging. Debugging results can acquire complete and undistorted flaw echo signals sent to PC, and display acquisition data using MATLAB,which proved the feasibility of the project.The paper for the ultrasonic signal design high-speed data acquisition system based on CPLD(EPM3064A) and DSP(TMS320F2812), DSP system which is the main control center, CPLD logic control is responsible for the entire system. The system provides a good hardware support for industrial ultrasonic flaw detection system and it provides a good solution for the development of digital flaw detector.