Research On The Method And System For On-line Measuring Wheel-set Dimensions By Laser

As the most important running components of the train,train wheels continuously rubs and collides with the steel rail during the train operation,resulting in wear and defects on its surface.With the continuous improvement of railway transportation in terms of running speed,the generation velocity of wear and defects is also accelerating,which bring an increasing impact on the safety of the train operation.The real-time monitor of the shape parameters of wheels and the wheel rail contact relationship can not only eliminate the potential safety hazards of the train operation,but also can reduce the maintenance costs of railway transportation system by optimize the maintenance actions.The real-time measurement of wheel-set dimensions is of great significance to ensure the safety of railway transportation and can realize the digital management of wheelset.It is the future development direction of railway transportation as the high accuracy and efficiency compared with manual methods.In this paper,with the support of the key project of the National Natural Science Foundation of China(51935002),the dynamic on-line measurement system of wheel dimensions is studied and the following achievements are obtained:(1)The key technologies in the on-line measurement method of wheel tread geometric parameters based on line structured light vision are studied,and the corresponding measurement system is developed.In the system,a photoelectric switch is used to realize the accuracy positioning of the wheel,two laser vision sensors are used to acquire the entire contour of the wheel tread.Then,an image processing program is developed to deal with the acquired image as as to calculate the wheel parameters such as flange height,flange thickness,QR value,rim width,inner distance and the pose of the wheel.According to problems such as light stripe aliasing caused by complex illumination conditions in field measurement,a laser stripe extraction algorithm and a fast calibration method of laser vision sensor are proposed,which not only improve the measurement accuracy,but also improve the robustness and practicability of the system.The experimental results show that this method is effective,and can adapt to the complex environment on site.The measuring device was installed on the railway site of Yinchuan application workshop in December 2017 which can realize accurate and rapid measurement of the wheel tread geometric parameters when the train passes the storage.The effectiveness of the method was verified by long time field measurements.(2)A dynamic on-line measurement method of wheel diameter based on laser displacement sensor is proposed.In this method,three laser displacement sensors are used to measure the wheel diameter combine with the tread contour data measured by the wheel tread geometric parameters on-line measurement system mentioned before.This method has the advantages of simple structure,high measurement accuracy and low cost.The results of railway field measurement show that this method can overcome the limitation of measurement position of on-line measurement,and can adapt to the complex environment on site.The wheel diameter measurement accuracy can meet the needs of railway department.(3)A wheelset wear model based on the measured data of wheel-set dimensions is proposed.The data measured by the on-line wheel dimension measurement system are used to analyze the wheel rail contact force,so as to calculate a more comprehensive train safety index and predict the wear behavior.Firstly,the multi rigid body dynamic model of the train carriage is established,the wheel is replaced according to the data of wheel tread profile,wheel diameter and wheel pose measured on-line,and then the wheel rail contact force is analyzed.This method provides a way for early warning of wheel wear overrun.