The Structure Design Of Suspended PRT Vehicle And Dynamics Research

With the increasingly number of the urban population density,the traffic congestion has become a major problem which hinders urban economic development and affects the normal life of residents.Developing public transport is one of the effective measures to solve the problem.The development of public transport needs to consider the individual characteristics of the city itself,and various transport systems should be able to complement each other.The Personal Rapid Transit(PRT),as a small-volume public transit system,makes up for the deficiency of the traditional public transportation system to provide special vehicle services.However,the system has not yet been used in China.This paper took the suspended PRT vehicle as the research target,according to its use requirements,designed the overall structure of the vehicle,and established a detailed threedimensional model for the running gear of the vehicle(ie,bogie)and the suspension device,and analyzed the force transmission process.At the same time,according to the relevant design experience,initially the parameters of the main suspension components of the vehicle,namely were selected,the vertical stiffness of a single spring damper was 20(N / mm).The lateral stiffness was 3.5(N / mm).The vertical damping coefficient was 900(N ?s / m),and lateral vibration damping coefficient was 230(N ?s / m).At the same time,the equivalent radial stiffness of traction rod was 904(N/mm)and the equivalent axial stiffness was 230(N/mm).Newton-Euler method was used to establish the theoretical dynamic model of the suspended PRT vehicle,and the Sperling stationarity index,the maximum lateral force of the guide wheel,the maximum vertical force of the travel wheel,and the maximum roll angle of the vehicle body were selected as the dynamic evaluation.Compared with the simulation model established by SIMPACK,the theoretical model considered less degrees of freedom,and at the same time,it simplified some components,so the calculation results were more ideal,but the variation trends of both were similar.To improve the running quality of the vehicle,the vehicle dynamics parameters were optimized by orthogonal test method and genetic optimization algorithm.In the orthogonal experiment optimization,the secondary quivalent vertical stiffness was 12.5(N/mm).Effective vertical damping coefficient was 700(N ?s / m).Secondary lateral equivalent stiffness was 1(N/mm).Secondary equivalent lateral damping coefficient 450(N ?s / m),and guide wheel radial stiffness was 90(N/mm).For the optimal combination of parameters,the secondary equivalent vertical stiffness was 10.2(N/mm).The secondary equivalent vertical damping coefficient is 692(N ?s / m),and the secondary lateral equivalent stiffness was 1.2(N/mm).Equivalent lateral damping was 243(N ?s / m),and guide wheel radial stiffness was 82(N/mm).Compared with the simulation results of the overall dynamics of the vehicle,the parameters of the genetic optimization algorithm were finally determined to be the most optimal.The selected optimization parameters have a greater influence on the stationarity.However,the maximum lateral force of the guide wheel and the maximum vertical force of the running wheel were less influenced by the opt factors.The lateral stability of the vehicle under unbalance load conditions would be reduced,and it would be lower than the no-load condition,while the vertical stability will be inferior to the no-load condition at partial speed level.The difference of the directional force between front and rear wheel became larger.In order to ensure safe operation,it was recommended to mount a balancing device on the vehicle body.