The Development Of Laser Triangulation Displacement Sensors For Wheel Measurement

The laser triangulation displacement sensors play an important role in the measurement of rails and wheels.With the rapid development of high-speed railways,a high-frequency and high-precision measurement for rails and wheels is desperately needed.This article investigated and analyzed the research progress of laser triangulation sensors at home and abroad.With the intent to develop the laser triangulation displacement sensors that is used for the measurement of rails and wheels,this paper take advantage of MATLAB to analyze the impacts between the optical parameter and the sensitivity of measuring system,as well as the resolution,the length of imaging and outline dimension.The theoretical instruction for the improvement of measurement speed and precision and the reduction of measurement cost obtained by these analyses.The first innovation of this paper is to change the traditional design concept that think of the imaging lens as thin lens.The influences of the position of principle planes on the image quality were analyzed and emulation analysis on the disadvantage of traditional design concept were done by the use of ZEMAX.The second innovation is to simulate and analyze the image quality of different lens with ZEMAX software.A reliable forecast for the linearity of the measurement system was proposed subsequently from the perspective of simulation image,and a proving experiment was conducted to verify the availability of the forecast method.The second innovation may provide a theoretical reference for the selection and optimization of image lens.The third one is to put forward a method to simulate the entire optical path of laser triangulation measurement with ZEMAX and Lambertian scattering model for the first time.The simulation model contains the power,the energy distribution and the divergence angle of laser,as well as the scattering property of object and the structural features of detector.With the simulation model,the influences of two kinds of object inclination on the measuring error and the causes of tilt error were analyzed.Three correction methods for tilt error were proposed,which give a significant reference for the installation and measurement.Besides the tilt simulation,the simulation model can also simulate the mechanical installation of the optical element such as line array CCD and analyze the measuring error derived from the variation of laser power,the color and roughness of the measured object.So the simulation model is of certain significance for the design of optical path,the selection of optical devices,the mechanical processing and installation,the analysis of measuring error of laser triangulation sensor.The paper has summarized the design experiences that are suitable for the special measurement requirements by the analyses and researches of laser triangulation.The prototype of laser triangulation sensor has applied to the measurement of rails and wheels,which will be a good market outlook.The design ideas related are of certain significance for the research on laser triangulation sensor.