Study And Design Of New Ultrasonic Array Circuit System For The Rail Flaw Detection

When the train brakes, accelerates,and goes through the welding seam, curves andswitches between the rails,the train will give friction, extrusion, impact and other forces to therails. When this happened repeatedly for long time,the rails will be easily cracked. And oncethese cracks expands rapidly, the severe accidents may happen.Therefore,to ensure the goodsreliability and personal safety,damage detection on the rail line to prevent disaster accident isextremely necessary.Against the limitations of domestic Hand push testing equipment and imported motordetection vehicle, combining with self-developed high-speed wide-band ultrasound transducerarray and new signal processing algorithm, our research group proposed a novel array railflaw detection structure and developed an ultrasonic rail flaw detection system with highdetecting speed and accuracy and low power consumption. Since the self-developedhigh-speed wide-band ultrasound transducer array and rail flaw detection services have thespecial requirements for driving circuits, and acquiring circuits, this thesis will developultrasonic transmitter receiver front-end and FPGA control system for a array ultrasonic raildamage detecting system. The thesis will focus on following problems:1. For better driving new ultrasound transducer array to generate wide-band ultrasonicsignals, a wide-band linear power amplifier was designed to drive the ultrasound probe totransmit the high-speed and wide-band ultrasonic detection signals after the continuous FMsignals were digital-analog converted,filtered and power amplified.2. To solve the problems of high-speed, wide-band, weak signal and lots of noises forultrasonic echo signals, a multi-channel weak signal low-noise high-speed acquisition circuitwas designed to receive6-channel weak ultrasonic echo signals simultaneously and performfiltering, low noise amplification and analog-digital conversion of the multi-channelultrasonic echo signals.3. Using FPGA to design a software digital controlling system, including the FM signalgeneration module, receiver front-end controlling module, and asynchronous FIFO module. In the design, the asynchronous FIFO was improved by adding an additional bit to the read andwrite pointer, and using Gray code and double latch synchronizer to solve the problem ofmetastability asynchronous clock and perform a high-speed store and processing of thereceived multi-channel weak ultrasonic echo signals.Finally, the thesis gives the test results and the analysis of the results. The outputpower of driving circuit can obtain more than1W, it can send test signals to the probeundistorted. The receiving circuit can obtain an adjustable gain of20-60dB,and can filterand amplify the multi-channel weak signals simultaneously.