Research On Control Strategy And Dynamic Performance Of Virtual Track Train

With the continuous improvement in urbanization level and rapid increase in urban population number,the resident trips in China increase significantly,which aggravates the burden on the urban public transport system.For some second-tier cities,their bus systems are insufficient to carry enough passengers,and their economy situation can’t afford to the high cost of the subway system.Therefore,a new passenger transport system with low cost and strong transportation capacity is urgently needed,and the virtual track train thus comes into existence.In this thesis,the control strategies and dynamic performances of the virtual track train are studied and the research work as well as the conclusions are summarized as follows.(1)The advantages and disadvantages of different programs for marshalling and running gear are compared and the results show that the structure with three marshalling floating car and double wishbone independent suspension has a good performance comprehensively,which meets the requirements in all aspects.(2)The tracking control method and the dynamic model for the virtual track train are developed on the basis of the proposed structure.The control strategies of all-axis coordinated,two-axis coordinated and single-axis coordinated are studied starting from the Ackermann steering geometry,and the best control strategy is selected and optimized by simulating analysis.The results show that the single-axis coordinated control strategy contains higher tracking control accuracy and better control stability,and is more suitable for the virtual track train.The control strategy after optimization overcomes the problem of steady-state deviation in curves,and improves the control accuracy and vehicle dynamic performance further.(3)The effect of the tracking control method and the dynamic performance of the virtual track train with the proposed structure are analyzed by the optimized control strategy and the established dynamic model.The results show that the tracking effect is perfect,and in the complex “∞” typed curve,the steady-state deviation is closed to 0 while the transient deviation is smaller than 100 mm.Furthermore,the dynamic performance of the virtual track train is also perfect.When it runs on the urban road within the speed range of 0～80km/h,the Sperling index for lateral and vertical directions are below 2.5,and the comfort index is below2.When it passes the curves,the lateral load transfer rate and the wheel unloading rate are far below the limit values of 0.8 and 0.65,respectively.