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Advanced Imaging Magazine

Updated: January 12th, 2011 09:49 AM CDT

In-Service Inspection of Locomotive Pantographs

Pancam analysis showing damaged carbon block and recognition of wire contact point.
Pancam analysis showing damaged carbon block and recognition of wire contact point.
Pancam RDC monitoring interface shows recent damaged and worn results.
Pancam RDC monitoring interface shows recent damaged and worn results.
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Hamey Vision (North Ryde, Australia)
QR Limited (Mackay, Australia)

The Challenge:

QR Limited's coal transport network employs electric locomotives with pantographs to draw electric power from overhead wires. Worn or damaged pantographs can damage the overhead wiring (dewirement) rendering the track unusable until repairs are complete, and may damage the locomotive or cause derailment. Current manual inspections are costly and insufficient to prevent dewirements. QR sought a trackside system to inspect the pantographs of electric locomotives in normal service, providing timely maintenance alerts day and night.

The Solution

The Pancam pantograph inspection system comprises software developed by Hamey Vision Systems and hardware developed by QR. Two digital cameras capture side and top views of passing pantographs. Using a white backboard, the side view is analyzed for the profile of the pantograph's carbon contact block, measuring wear and detecting notches and step wear patterns that could damage the overhead wiring. The top view is analyzed to inspect the pantograph's horns. Meanwhile, an AVI tag reader captures the locomotive ID. Pancam uses a multi-threaded design to quickly capture data and then analyze it within minutes. Pancam's analysis techniques are rapid and effective, combining pattern matching to recognize different pantograph types with segmentation and morphology to analyze wear and damage. Variations in pantograph position cause perspective scaling, so wear measurement is adjusted based on the point of contact of the pantograph with the overhead wire. Inspection images are saved to a file server and results are stored in a database. A web interface promptly notifies QR's Rollingstock Defect Coordinators (RDCs) of wear and damage results. RDCs then can view the inspection images and forward maintenance requests to maintenance staff. Autonomous operation of Pancam is assured by software and hardware watchdog facilities.

The Tools Used

  • Halcon v7.1 machine vision library distributed by MVTec Software
  • Imperx IPX-2M30H-G monochrome CCD digital cameras
  • Metal halide discharge lamps
  • Infrared sensors
  • AVI tag reader
  • Microsoft SQL Server 2005 Express edition SP2
  • Apache Web server with PHP 5
  • Existing network infrastructure

The Difference it Made:

QR estimates that dewirements cost at least $1 million (Australian) each in lost service time of track and locomotives, lost rail system throughput and repair costs. In 20 months of operation, Pancam has prevented all pantograph-related dewirements on the rail network it monitors, yielding benefits in excess of $20 million (Australian). This is a significant ROI for QR and for the Australian coal export industry. Other benefits of Pancam include helping to ensure that pantographs and the overhead wire are maintained in peak operating condition through timely maintenance, eliminating the need for manual inspection, and providing accumulated historical data for each locomotive pantograph.



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