Basic study on improving the efficiency of pantograph slider inspection operations using SfM

In Japan, electric train inspections and maintenance involve workers climbing onto the roof and visually inspecting the wear of the pantographs' current collector strips. To conduct this work safely and efficiently, inspection methods using sensors are being developed. However, existing methods assume daytime inspections and face challenges related to sunlight conditions. Therefore, if measurements can be taken at night or indoors, where changes in sunlight conditions are minimal, it would contribute to the efficiency of inspections. In this study, we proposed a method to measure the wear of current collector strips at night by projecting patterns onto the strips and generating a point cloud from multi-view images of the projected patterns on the strips. In a demonstration experiment, we used current collector strips that were actually in use by the railway company to confirm the presence of wear. As a result, it was found that the proposed method can determine the wear amount of the current collector strips with an accuracy of about 1 mm when the vehicle is stationary.