Research on application of Scheimpflug condition in rail profile measurement

Abstract

In recent years, structured light measurement technology has been widely used in rail profile measurement. Due to the small depth of field of the conventional rail profile measurement with linear structured light, the imaging problem of defocusing blur occurs in the area of rail waist and rail bottom, which leads to low accuracy of rail profile measurement. Therefore, the Scheimpflug condition is applied to the rail profile measurement system with linear structured light, and a constant focus optical path for rail profile measurement is designed. The results show that compared with the conventional measurement optical path, the depth of field of the imaging system is expanded from less than 90 mm to 210 mm, the width of the light strip at the rail waist and rail bottom is reduced and the energy is more concentrated. At the same time, the clear imaging of the rail head, rail waist and rail bottom is ensured, and the rail profile measurement error is reduced from 0.094 mm to 0.071 mm. This method can solve the problem of low measurement accuracy caused by defocusing blur in traditional measurement optical path, and provide a reference for the application of Scheimpflug condition in rail profile measurement.