<title>CCD photonic system for rail width measurement</title>

Abstract

At present, in Moscow metro a track inspection vehicle, defectoscope and portable measurement instruments are used to measure the rail profile and the condition of track. The track inspection vehicle measures 8 parameters, such as rail height, width, lip flow, cant, gauge and rail identification. The main drawback of the existing track control devices is a contact mode of measurement that does not provide required accuracy during the movement of the track inspection vehicle. This drawback can be eliminated using the non-contact photonic system (NPS). NPS consists of four special digital CCD-cameras and four lasers (two cameras and two lasers on each rail), rigidly connected together and mounted underneath the rail inspection vehicle in such a manner that corners of vision and distances from the cameras up to the head of the rail remain fixed during the movement. A special processor is included at the output of each camera. It performs preliminary processing of the stripe image on the appropriate side of a rail and then codes (compresses) and transfers data to central computer. The central computer executes the rail profile restoration and its comparison with the pattern of the rail on the particular section of the track.