Contact Wire Non-contact Detection System Based On Line Scan CCD Camera

Electrified railway is universally concerned with its advantages of low cost, little environment pollution, high speed and so on. The contact wire, as one of the most important components in the system, its state pros directly affects the safe operation of electrified railway. Therefore, to ensure the Electrified railway operate safely, finds out the existing problems and potential risks, the contact network state detection is an indispensable work.A contact wire fixed-point monitoring system used in electrified railways is put forward in this paper by tracking the trend of catenary dynamic detection domestic and overseas and considering the features about high-speed catenary detection fully. This detection system can be used to monitor the state of the catenary and to determine the occurrence of defects in the pantograph-ocs system and by measuring the real-time dynamic height of the contact wire. Through reasonable location design of the line scan CCD camera and the lighting source, the video image of the contact wire can be acquired from line scan CCD camera in9.5kHz. Then the dynamic height of the contact wire can be derived out from the video image by the edge detection algorithm and the moving object treatment technique. This detection scheme overcomes the large disturbance limitation of the vehicle on-board detection and the contact detection based on the displacement transducer, and has an improved precision.According to the line scan camera scanning frequency, the hardware scheme of designing high-speed data acquisition system is discussed and implemented with FPGA as control unit to acquire and transmit data accurately. Based on machine vision system, an algorithm for subpixel edge detecting is adopted for the CCD image, by virtue of computer image processing technology. According to the pixel position, we can accurate the contact wire position in existence. By real-time target tracking system based on PC software design, we can track the height of the contact wire on-line, and alert when the emergencies happen. The results showed that the non-contact detection are more effective、reliable and sensitive compared with the traditional technology.