Rail Surface Inspection System Using Differential Topographic Images

In this paper a surface inspection system for rails is presented. Rails must meet the strict requirements of international quality standards, however there are few commercial surface inspection systems for rails and also, a lack of publications describing the design and configuration of inspection systems in detail. Therefore, manufacturers must develop their own systems or buy one of the few commercial ones available. These systems also need a long, cumbersome and expensive configuration process the manufacturer cannot perform without the assistance of the inspection system provider. The system proposed in this paper needs a set of samples and the requirements of the international standards to carry out an automatic configuration process avoiding the cost of manual configuration. The system uses four profilometers to acquire the surface of the rail. The acquired data is compared to a mathematical model of the rail to generate differential topographic images of the surface of the rail. Then a computer vision algorithm is used to detect defects based on the tolerances established in the international quality standards. The system has been tested and validated using a set of rails and a rail pattern from ArcelorMittal, with better results than the other two systems installed in a factory.