Customer SolutionsLabVIEW Accurately Measures Condition of European Channel Tunnel Infrastructure
Author(s):Gerard Delacre, Eurotunnel; Veronique Newland, New Vision Technologies Inc.
Industry:Transportation
Product:LabVIEW, Vision
The Challenge:Measuring wear on the electrical contact cabling inside the Channel Tunnel without disrupting traffic.
The Solution:Using NI LabVIEW, the NI Vision Development Module, and the NI Compact Vision System to design an embedded imaging process capable of taking accurate optical measurements quickly and without interrupting service.
The Channel Tunnel is a 50-km, twin-bore rail tunnel that runs beneath the English Channel at the Straits of Dover, connecting Folkestone in Taking Measurements without Disrupting Operation In 2004 alone, more than 16 million rail passengers traveled through the Channel Tunnel. We needed a method to measure the wear on the 100 km of electrical contact cabling inside the tunnel without disrupting rail traffic, and to simultaneously measure the position, height, and width of the contact wear on the cable. We were able to solve both of these challenges using National Instruments LabVIEW, the NI Vision Development Module, and the NI CVS-1454 Compact Vision System, along with a high-speed IEEE 1394 (FireWire®) camera. We chose the Compact Vision System with NI LabVIEW and the NI Vision Development Module to combine the power and reliability of an embedded vision system with the flexibility of LabVIEW. Capturing the Images The contact cable is illuminated by a metal halide high-output light source that causes any areas where the cable is wearing out to appear shiny on a dark background. The images are captured by a CMOS monochromic area scan camera with an IEEE 1394 output, which can acquire up to 500 frames per second in a 640x100 pixel format. The CVS-1454 Compact Vision System then grabs the frames and processes the images with the NI Vision Development Module, and we can determine the width of the wear area by thresholding the contact cable in the frame. The 640-mm width of the field of view (FOV) covers the maximum offset of the cable and the 100-mm FOV height is enough to measure the overall cable wear. We can measure the width and position of the cable 100 times per second, and the data is stored to a monitoring PC every 50 millimeters. In order to avoid light level variations, the threshold level is adjusted as a function of the cable’s position in the image. One of the most challenging obstacles we faced was developing the vision system so that it could be installed and configured within a very short time in the tunnel, between trains. Using LabVIEW and the NI Vision Development Module, our engineers can develop and test the processing software on a PC-based Windows platform using a library of images previously recorded in the tunnel. The same code can then easily be transferred to the Compact Vision System. LabVIEW and the Vision Development Module also make it easy to update the image processing software on the Compact Vision System. For example, adding image logging to record special faults or anomalies on the cabling was very straightforward. Also, the modular hardware and software approach means that we can add additional Compact Vision Systems in the future to measure and inspect other elements of the infrastructure, such as dropper points, rail, and track geometry. Eurotunnel regularly conducts maintenance operations to ensure the security and safety of the railway. Using this system, our engineers can easily and efficiently measure the position and wear of the contact cabling, detecting and repairing any abnormal displacement or damage that could cause cable rupture and failure. For more information, contact: Gerard Delacre, Eurotunnel E-mail: gerard.delacre@eurotunnel.com
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