Laser Visual Dynamic Measurement of Rail Wear on Complete Profile

Rail wear directly affects the safety of the railway transportation. To replace the current manual measurement methods and improve the measurement accuracy and efficiency, a laser rail full-profile visual measurement system was researched and designed to realize the dynamic measurement of rail wear. Firstly, the hardware structure of the laser measurement unit was designed by calculating laser vision measurement model. Then, the checkerboard plane calibration method was used to precisely calibrate the laser measurement unit to obtain the projection relationship between the laser plane and the camera plane, so the laser image of rail profile could be converted to the actual profile of rail. Based on the same characteristics of rail head profile on both sides at the same section which could be extracted by Euclidean clustering and distance segmentation, the full profile of rail section could be synthesized by ICP registration method. Finally, the waist contour and characteristic points of the unworn rail on both sides were taken as the datum, the full profile of the measured rail was compared with the standard rail profile, so rail wear was calculated from the difference between them. The laser measurement units were mounted on a self-developed rail measurement trolley for field measurement tests. The results show that the calibration accuracy of the measurement system can reach 4.922 × 10⁻³ mm and the measurement speed can reach 21.6 km/h. Compared with the rail wear gauge, the average deviation of vertical wear and horizontal wear of this system is 0.023 mm and 0.093 mm. The maximum deviation of the system for repeated measurement of the same object is less than 0.05 mm. The new system meets the demand of rail wear measurement, improves the measurement efficiency, and is convenient for the digital management of railway survey.