A Multiline Structured Light Sensor-Based System for Measuring the Geometries of Train Wheelsets

The wheelset is a critical component of a rail vehicle, carrying the weight of the train in contact with the rail during the train operation. The constant measurement of wheelset geometries is required to ensure safe train operation. This article presents a wheelset geometries measurement system based on multiline structured light sensors. First, the principle of the system is introduced. Second, a 2-D calibration target with circular markers is designed to calibrate the camera and extract the centerline of the light bar in light interception image. A special bright block region is used to complete the structured light matching to complete the calibration of the light plane. Then, a method for obtaining the tread curve based on the radius of the circular cross section is described to obtain wheelset geometries, converting the problem of fitting a 3-D sphere radius to a 2-D plane. The system was implemented at Shihu Station on Guangzhou Metro Line 14. The results show that the presented system can measure different wheelset geometries with an accuracy of 0.5 mm for wheel diameter and 0.2 mm for flange thickness and flange height, better repeatability, and cheaper compared to other systems and manual measurements.