High-speed imaging and processing for rail track inspection

Abstract

The safety of railway traffic depends on state of the track. About ten parameters are measured on Moscow Metropolitan for rail control. At present time the contact technology is used that doesn't provide required accuracy, limits speed of movement up to 25 mph and doesn't work in real-time mode. Non-contact photonic measurement system (KSIR) is developed which can works at speeds up to 70 mph. The KSIR consists of four subsystems: rail wear, height and track gauge measurement (BFSM); rail slump measurement (FIP); contact rail measurement (FKR); speed, level and car locating (USI). KSIR contains five CCD matrix cameras, four line CCD cameras, five infrared stripe lasers and four spot infrared lasers. Preliminary image processing is carried out using digital signal processor. The images from cameras are distorted because there is angle between photonic unit and rail. Additional distortions are caused by short-focus optics and small distance between camera and track. This distance is limited by structure clearance. For distortion eliminating is applied the transformation algorithms. It's based on surfaces spline-approximation. As a result the KSIR calculates coefficients of approximating polynomials. The calibration is performed for checking accuracy of measurement in BFSM, FIP and FKR units.