Research On Measurement Method Of Point Rail Profile Based On Line Laser Sensor

With the continuous improvement of railway operating mileage in China,the method based on non-contact optical measurement shows a strong potential for popularization and application with its advantages of high efficiency and high precision.However,at present,this measurement method is only widely used in the profile measurement of ordinary rail,and the point rail at the junction of two tracks has brought difficulties to the profile measurement because of its variable section and complex structure.The traditional caliper method is mainly used for measurement.This contact measurement method has many problems,such as low efficiency,greatly affected by human factors and incomplete data collection.Therefore,based on the existing research on the profile measurement of ordinary rail,combined with the processing method of laser scanning point cloud data,this paper proposes a measurement method of point rail profile,and obtains the reduction value and wear amount of point rail under any section.The main research contents and results are as follows:(1)The overall planning and design of the core rail profile measurement system are completed.The geometric profile characteristics of the point rail and the wheel rail contact state are analyzed,and the main requirements of the point rail profile measurement are defined;The data acquisition scheme of the hardware part of the measurement system and the data processing flow of the software system are completed;Finally,the data processing and analysis interface of each module of the measurement system software is designed.(2)The noise reduction and reduction methods of measured point rail point cloud data are studied.Three discrete noise removal algorithms are compared and analyzed.According to the intuitive comparison results,the chord height difference method is selected to eliminate discrete noise;Three smoothing algorithms of mixed noise are compared and analyzed.Combined with the visual comparison results and quantitative evaluation criteria,Gaussian filtering method is selected to eliminate mixed noise;Four kinds of data reduction algorithms of linear laser scanning point cloud are compared and analyzed.According to the specific evaluation criteria,the adaptive minimum distance method is selected to compress the data of point cloud.(3)The registration and curve fitting methods of measured point rail point cloud are studied.The commonly used point cloud coarse registration algorithm is used to coarse register the measured point rail point cloud data.Combined with the geometric surface characteristics of the point rail and the characteristics of the measurement scheme,a coarse registration algorithm suitable for the point rail point cloud is proposed;On this basis,the optimized ICP algorithm is used to realize the precise registration between the measured point rail point cloud and the standard point rail surface,which improves the accuracy and efficiency of registration;The measured cross-section profile of the point rail is fitted,and the low value of the decline and wear of any section of the point rail are calculated.The accuracy of the measurement system is verified by experiments.