Research On Steering Problems And Control Methods Of Different Modes Of Urban Ground Rail Transit

With the rapid development of China's economy,the quantity of urban population has dramatically increased,leading to a sharp increase of urban public transportation demand.Urban public transportation mainly contains the buses and the rail transit.Buses bring out environmental pollution,traffic jams and traffic accidents.Therefore,rail transit is the future development direction of the urban public transportation.Urban rail transit mainly contains the subway,sky train and ground rail transit.Comparing with the subway and the sky train The construction cost of the urban ground rail transit is lower,which is very attractive to the small and medium-sized cities.Nowadays,the technology of urban ground rail transit is continuously innovating and developing.This dissertation will conduct an in-depth research on the steering technical difficulties faced by the running system during the development of the urban ground rail transit,the main research contents are as follows.(1)The development the urban ground rail transit is analyzed.According to the research status and technical characteristics of the urban vehicles,the development trend of the urban ground rail transit is summarized as steel wheel/rail?rubber tire and steel guiding wheel?virtual track.(2)The steering problems of the different running modes of the urban ground rail transit are studied.During the development process of the urban ground rail transit,different modes of the running systems face a common technical problem,that is,the steering performance.It is also a technical main route of this dissertation.Therefore,an in-depth analysis on the steering problems of the three typical running modes in the development process of the urban ground rail transit is conducted to support the subsequent chapters.(3)The steering control method of the urban rail transit with steel wheel/rail running system is researched.The steel wheel/rail running mode corresponds to the first stage in the development process of the urban ground rail transit.An in-depth research on the steering control technology of the steel wheel/rail running mode of the urban ground rail transit is conducted: The vehicle conducted with low-floor independent rotating wheels.Due to the lack of longitudinal creep force,the wheels have no effort to self-steering.The guiding mechanism of curving is analyzed,the synchronous/asynchronous rotating control method is proposed,and the recommended values of the control coefficient on different radii are given to improve the steering performance of the running system.(4)Research on the steering control method of the urban rail transit with the rubber tire and steel guiding wheel running system is conducted.The rubber tire and steel guiding wheel running mode corresponds to the second stage in the development process of the urban ground rail transit.The steering control technology of the rubber tire and steel guiding wheel running mode of the urban ground rail transit is studied in depth: The vehicle is carried with the rubber tires and guided with the steel wheels,driven by the hub motors so that cannot be directly installed with the mechanical differential.Based on the preview idea,a closed-loop speed feedback control method is proposed.Compared with the natural differential speed characteristics of the motor,the running system driven by the electrical differential speed control has better guiding performance.The influence of the key parameters of the steering system is analyzed,and the recommended values are given.(5)The steering control method of the urban rail transit with the virtual track running system is studied.The virtual track running mode corresponds to the third stage in the development process of the urban ground rail transit.An in-depth research on the steering control technology of the virtual track running mode of the urban ground rail transit is conducted: The vehicle is carried and guided by the rubber tires with the virtual track.Based on the lateral deviation of the tracking point,a feedback compensation control method for the steering yaw angle is proposed.Based on the vehicle kinematics,a feedforward speed control method is proposed.Based on the wheel relative slip ratio,a coordinated longitudinal/lateral multi-wheel control method is proposed.The simulation of the vehicle tracking deviation using the ‘yaw+speed+torque' steering control method is analyzed,and the recommended values of the control key parameters are given.