Study On Kinematics And Workspace Of Three Six-Dof Platform Of High-Speed Train Bogie Test Bench

It’ll be an inevitable trend for the development of railway transportation to increase therunning speed and carrying capacity. Thus the problem of vehicle vibration caused by railirregularity has become more and more prominent. The performance parameters of the bogiewhich worked as the walking mechanism of vehicle have a marked impact on theperformance of vehicle security, stability and dynamics. Hence, it is crucial to design bogiewith high performance and optimize the performance parameters of current bogie to increasethe running speed and carrying capacity.The development of bogie comprehensiveparameters test bench of high-speed train is essential to the manufacture of bogie product,the optimizing of the structure, the theoretical and experiment research, the control of qualityand shortening the product development period. Consequently, many research institutionsand car factories both at home and abroad promote development work on the bogieparameters test bench.This thesis is based on the project named high-speed untaken by vehicle transportationinstitute of Jilin university. Its devoted to the research on the kinematics and workspace ofthe bogie6-DOF platform of high-speed train which can improve the performance of thebogie comprehensive parameters test bench and provide effective theoretical foundation andtechnical support for accurate simulation of the bogie operating pose. As a result, theresearch is of great significance to the design and development capabilities of high-speedtrain. The following is the main contents of this thesis.1. It mainly discussed about the detection technique of bogie parameters anddevelopment state of6-DOF movement platform, inverse displacement solution andworkspace both at home and abroad. After analyzing the limitation and shortage of thesetechniques, this thesis put forward the importance of the research and presents the function,system constitution and key techniques of the bogie comprehensive parameters test bench indetails.2. Time history function about vertical and nodding operating pose of the bogie wasbuilt.Take train vertical vibration as an example, combined excitation characteristics of railirregularity, the reduced and decoupled bogie dynamitic characteristic equations wereestablished by analysis of vertical kinetics and dynamic decoupling algorithm in actual operation. In the meantime, the time history function model about vertical and noddingoperating pose of the bogie was achieved by method of solving non-homogeneousdifferential equation and Cramers linear equation, laying a foundation for nc electrohydraulic servo excitation system realizing iterative control of rail irregularity indoorsimulation and the bogie dynamitic characteristic in actual operation.3. This thesis presented a theoretical research on indoor simulation methods of typicalroute geometry information.Combined with geometry behavior of track torsion irregularityand structure characteristics of simulation platform, it presented a theoretical research onindoor simulation methods of track torsion irregularity at diverse velocity, motonaga andamplitude. At a same time, a mathematical model of simulating operating post changed withtime was established, providing basis for methods of indoor simulation of track torsionirregularityTake slope line geometry information as an example, it discussed about the slope，theand indoor simulation methods of track torsion irregularity based on slope line geometryinformation and finally changed slope line geometry information of space domain into theplatform pose of time domain.4. This thesis presented a study on the modeling and solving method of the bogie6-DOF operating pose.When the assumption that the platform can be regarded as rigid bodywas verified by the static analysis results of6-DOF platform, combined with the installationposition and defects of required level and other parameters determined by geometricparameters of the three6-DOF platform. The wheelbase and parameters of bogie, the inversedisplacement solution mathematical models of upper and lower platforms were established,as well as the pose reverse models of the union movement of three platforms and errorcorrection based on the homogeneous coordinate matrix and vector norm method. With thehelp of Simulink, the simulation model of inverse displacement solution was built based onthe movement of upper and lower platforms, the union movement of three platforms,transport motion and relative coupling motion. Finally, it realizes real-time solving of theactuator expansion amount on any cases. From the example, it analyzes the changeregulation of actuator expansion amount and verifies the accuracy of the mathematical modelof inverse displacement solution and simulation model by calculation results based ongeometric theory.5. This thesis researched on the workspace of the bogie6-DOF platform using thesolving method of parallel mechanism workspace. From the point of view of optimization,put forward a kind of method to testing the collision of static convex polyhedron and dynamic convex polyhedron. By introducing spatial kinematics and spatial convexpolyhedron representation theory, the method put the problem of detect whether the dynamicand static two convex objects produce the movement interference or not translate intosolving the nonlinear programming problem of the shortest distance between two objects, bycalculating the shortest distance value to determine whether two objects are in a pose ofcollision. Proposed the collision detection model of constant size object and variable sizemoving object with the spherical pair constraints in two different conditions, it providedtheory evidence for the same size of object and variable size moving object collisiondetection under the spherical pair constraints or other circumstances.6. Finally, the test of center-of-gravity position measurement and indoor simulation oftrack torsion irregularity was conducted. It put forward a method for measurement ofcenter-of-gravity position based on the weight feedback method and moment balance theory.Meanwhile, the gravity center mathematical measurement models in transverse position,longitudinal position and vertical position of the platform in horizontal position wasestablished and the test for measurement of center-of-gravity position is proposed whichcontains the test condition, requirement and procedures. Moreover, with the help of theplatform, the test of center-of-gravity position measurement and indoor simulation of tracktorsion irregularity was conducted, as well as the test of wheel unloading rate and torsionalstiffness of the bogie.The research result of this thesis is devoted to the bogie parameter determination testbench. With the objective of realizing dynamic simulation and high-speed train bogiesparameter determination, it can provide a foundation for the development of new bogies andthe testing of bogie dynamic behavior. Based on the demand of CNR Changchun RailwayVehicles Co., Ltd, such as new product development, performance testing and failurediagnosis, this thesis is of some practical engineering value. Moreover, the position solutionand the workspace search method of the6-DOF platform bring forward ground for realizingthe bogie operating pose, as well as provided effective theoretical foundation and technicalsupport for accurate simulation of the bogie operating pose and workspace analysis of otherforms.