Research On Dynamic Envelope Curve Measurement Of High-speed Train

Dynamic envelope curve, a key basis for defining the dynamic gauge, is definedas the maximum limit outline affected by a variety of adverse factors while the train isrunning. With the speed of the high-speed train lifting continuously, the conflictbetween the strict requirements in traffic safety for the authenticity of dynamicenvelope curve and the inaccurate methods for dynamic envelope curve measurementis increasingly prominent. It is imperative to obtain dynamic envelope curveaccurately by the measuring method.According to the profound analysis of the definition of dynamic envelope curve,this article proposes an idea based on the static measurement of train body outline andparameter measurement of dynamic posture, aiming to resolve the measurement ofdynamic envelope curve of high-speed train. Concerning the technological problem ofthe measurement of dynamic posture while the train is running at high speed, amethod of calculating parameter of dynamic posture is proposed, by means ofmatching dynamic outline with static curve surface. Then, intensive study isconducted into dynamic posture calculation, static reference profile and curvemeasurement, dynamic outline measurement, reference section estimation of dynamicposture, field calibration and other key technologies based on surface matching.Experimental verification has been carried out to provide theoretical basis and datasupport for measuring dynamic envelope curve of high-speed train at field. The mainwork accomplished includes:1. The active demand and also characteristics of dynamic envelope curvemeasurement for high-speed train are summarized. Concerning the limitation ofexisting calculating and measurement methods of dynamic envelope curve, and withcomprehensive consideration of theoretical research and practical application, amethod for dynamic envelope curve measurement is proposed by using referenceprofile and dynamic posture, and following research has been carried out.2. Key technology and related algorithm of surface matching have been studied.Aiming at obtaining dynamic posture by means of matching dynamic partial outlineand partial surface, dispersion index mapping and expanding index mapping are introduced, with expanding index mapping brought in matching. Modified ICPalgorithm for curve matching and surface matching is proposed. The effectiveness ofthe method is tested and verified by experiments.3. By analyzing the structure and manufacturing technique of the high-speedtrain, the measurement method of profile scan based on distance measuring isproposed. Reference curve surface generation method is proposed on condition ofrationality assumption. Measurement platform is constructed to verify the feasibilityand accuracy of the measurement method.4. The Measurement method of dynamic partial outline based on principle ofbinocular vision is proposed. Detailed researches on camera calibration, extraction oflight stripe, stereo matching and other key technology are carried out. Deep analysison binocular vision measurement errors and dynamic measurement errors is made.The feasibility of field measurement and measurement accuracy is tested and verifiedby experiments.5. Errors and their influence in dynamic posture parameter of reference sectionestimated by location information are explained and analyzed. Maximum error isobtained by quantitative analysis and the reliability of method of estimation is testedand verified.6. On the issues of the unity of both static and dynamic measurement coordinates,the effect of common points layout on coordinate transformation is studied bycoordinate transformation modeling. Constraints of railway interests are fullyconsidered on condition of guaranteed precision, and a quick calibration methodapplicable in the field is proposed.