Using triangulation laser scanners to monitor the condition of railroad tracks

In order to measure the geometrical parameters of railroad track, one needs to know the position of the heads of the left and right rails—in particular, the point of the rail 14 mm below its rolling surface. The use of triangulation laser scanners to carry out this task involves the problem of intense noise in the resulting images as a consequence of sunlight and the “moon-glade” effect on the rail’s smooth surface. An approach to the measurement of the railroad-track parameters is proposed, based on the recognition of images under railroad conditions and using supplementary structural and algorithmic resources, including the extraction of information from other sensors of the system (strapdown inertial navigation system, odometer). The methods proposed in this paper, in combination with the processing algorithm derived here, make it possible to determine the positioning of the rails to within 0.1 mm.