Research On Vision Measurement Technology Of Axle Of High-speed Train

High-speed train has been a very important transport for travel and willplay a more important role in industry and people’s daily life. As the speed oftrain become faster, the requirements for qualities of components’manufacturing have become more serious. The two relative wheels are used toconnect the train and rail way, bearing the dynamic and static load of the train.Both the two wheels are linked by an axle. So the axle is on of the mostimportant component for the safety of vehicle. Considering inspection of axle’ssize in the machining and assembly processes, a visual inspection method hasbeen proposed based on the multi-line structured light, in order to detect thediameter of axle in real time.The visual inspection and axle measurement technologies have beenresearched deeply in this paper. The axle inspection has been achieved based onstructured line visual method that used laser triangulation. The inspection systemis composed of a camera, a semiconductor laser projector, a calibration plate, a pictureacquired card and a computer. At the time of measurement, the laser projector projectsthe light plane to the tested axle. Both the light plane and the surface of axle areintersected to form light arcs, so the three-dimensional coordinates of the points inlight arcs have been defined. The respective centers of oval are available by utilizingthe known points in the multiple arcs on the oval through fitting method. Then theaxle line is obtained by way of fitting a three-dimensional straight line used twoarbitrary points in the centers. The plane perpendicular to the axis is gotten that isthrough a arbitrary point in the axle. The projected points are formed via projectingthe arcs cross-section to the plane. The parameters of diameter will be known afterfitting an circle among the projected points.According to the working principle of inspection system, the measurement modelof this system is been built. A kind of improved quantum particle swarm optimizationis selected to calibrate and optimize the parameters’ of camera after analyzing variouscalibration algorithms. Virtual three-dimensional calibration template offering high precision controlling points to the calibration has been built by infrared light-emittingdiodes and coordinate measuring machine. So the calibration of camera parameterscan be optimized globally with high precision. The light sensor that is also calledplane parameter equation of laser projection light can be calibrated by planar targettemplate line structure. Since the calibration template can move freely within thescope of the field of view, the occlusion problems in traditional calibration can beresolved and the calibration process run simply with high precision. The edgeextraction of black hole on calibration template can be implemented by space momentmethod and can be located precisely with edge fitting method. At the same time, theaccurate center position in inspection light strip can be found through Hessian matrixmethod.The results of axle inspection experiments show that the inspection systemproposed in this article is stable, precise and feasible.