Structured-Light Binocular Vision System for Dynamic Measurement of Rail Wear

Accurate and efficient measurement of rail wear is critical to the safety of railway system. However, it is a challenge to obtain the full profile of rail and measure rail wear by using the vision system on site. Based on structured-light visual technology, a novel structured-light binocular vision system was developed to obtain the full profile of rail and realize the rail wear measurement more accurately and efficiently on site. Firstly, camera automatic exposure and Hessian matrix were combined to eliminate the influence of ambient light, through which the sub-pixel coordinates of the rail profile light strip center can be accurately extracted. Secondly, the free plane target was used to achieve the binocular calibration of the measurement system so that the full profile of rail can be acquired rapidly. Finally, PCA (Principal Component Analysis) and ICP (Iterative closest point) registration methods were utilized to compare the measured rail profile with the standard rail profile for the acquisition of accurate rail wear value. The experimental results showed that vision measurement of rail wear on the full profile of rail was realized and the measurement accuracy of rail wear reached 0.1 mm.