| With the development of track broken detection technology,the use of ultrasonic guided waves(UGW)to detect the broken tracks has received great attention.In the UGW-based track broken detection system,the ultrasonic transducers are used to transmit and receive UGW signals,the accuracy of ultrasonic transducer installation can affect the efficiency of track broken detection.The existing UGW-based track broken detection system is still in the development stage,there is no equipment to detect the installation of ultrasonic transducer.Therefore,some problems occurred in the installation of ultrasonic transducers can lead to false alarm for the UGW-based track broken detection system.To solve these problems,this work propose a portable detector to check the installation of ultrasonic transducers.In this paper,the problems existing in the installation of ultrasonic transducers are analyzed firstly,the functional requirments of detector are put forward.Based on the obtained signal information from UGW-based track broken detection system,the detection standard for the detector is proposed.According to the standard,through detecting the received signal which is 1m far away from the ultrasonic transducer under test,whether the transducer is installed correctly can be estimated.The hardware of proposed detector mainly includes UGW transmitting circuit,receiving circuit,STM32 main control circuit,as well as LCD display circuit and so on.STM32 output control signal to drive MOSFET's opening/closing,then to generate the impulse signal.This impulse signal is amplified by transformer and can output high voltage impulse signal.Then,the high voltage impulse signal drives the ultrasonic transducer under test to generate UGW signals.Through the transmission of lm track,the UGW signals arrived at the receiver of proposed detector.The received signals are processed by receive circuit and are sent to A/D module in STM32.The software part mainly incudes the transplanting of ?C/OS-? system,the design of the StemWin human-computer interaction interface,as well as the acquisition and processing of the received signal.The signal collected by ADC in STM32 is processed by FIR filter and FFT processing,its time-domain curve and amplitude-frequency curve can be displayed in the LCD human-computer interaction interface.Based on the detection standard,the installation result of ultrasonic transducer can be displayed in the screen.At the end of this paper,the hardware and software debugging of the proposed detector is completed by building test platform in the laboratory,the correctness of each function module is verified.At the same time,the experimental scheme is designed to verify the influence of the drive signal,the thickness of the coupling agent,as well as the fitting degree of the transducer and track on the installation of the transducer.Finally,the actual installation test at the outdoor railway line is put forward.According to the correctness of received signal and the result of the detector displayed,the fact that the detector designed in this work can be used accurately and reliably to detect transducer installation is proved. |
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