The issue of uncertainty of visual measurement techniques for long distance measurements based on the example of applying electric traction elements in diagnostics and monitoring

Rail transport is the most economical and energy-effective in the field of land transport, in particular electrified. In order to ensure efficient and reliable operation of electrified rail transport, the issues of monitoring and diagnostics of the traction infrastructure and vehicles are extremely important. The most critical point in the transmission of electric energy to the vehicle is the sliding contact of the current collector with the traction network. For this reason, work is currently being carried out on the possibility of monitoring the technical condition of current collectors at selected points of the railway lines, which makes it possible to detect the current collectors which do not work properly, and those in which the damage occurred after the train's departure. In order to make the diagnostic process at such point as complete as possible, it is necessary to develop new measurement methods and new applications for the existing methods. Evaluation of the technical condition of current collectors at the control point is carried out based on the analysis of displacements of the contact wire of the overhead contact line, caused by the impact of the current collector. The nature of these displacements, as well as the presence or absence of certain components provides the information on the correct adjustment of the current collector and the technical condition of its strips. Simultaneous measurement of vertical and horizontal displacements requires the application of innovative measurement techniques. The use of non-contact visual techniques for this purpose, which makes it possible to measure displacements in a two-dimensional plane using a fast 2D camera and advanced image analysis, is promising. This article presents the analysis of measurement uncertainty of visual measurement techniques for long distance measurements for application of electric traction element diagnostic and monitoring. The measurement verification at a laboratory test stand are also presented. The requirements concerning the measurement equipment have been determined and the factors affecting the uncertainty of the final measurement dependent on a given configuration of the stand have been specified.