Research On Active Steering Control Of Multi-unit Train-like Vehicle Trailers

Multi-unit train-like vehicle is a kind of subversive transportation between bus and rail transit.It is an important transportation solution for improving transportation efficiency and reducing pollution emissions.However,due to its multi-unit and multi-articulated point characteristics,the dynamic performance of the whole vehicle is complicated.In the course of operation,it is prone to instability such as "folding"and "snaking motion",which seriously affects road safety.For a four-unit six-axle train-like vehicle of a certain enterprise,a trailers cooperative active steering control method for train-like vehicle based on LQR control principle is proposed,and the following work is carried outIntroduced the main structure of the train-like vehicle with active control,analyzes the dynamic characteristics of the articulated plate,and uses Adams/Car software to establish a virtual prototype model of a four unit six axle train-like vehicle including suspension,transmission system,steering system,power system etc.The lateral motion formula of the vehicle unit in the vehicle coordinate system is derived.The mathematical model of the tire based on the linear magic formula is selected.The five-degree-of-freedom linear simplified lateral motion differential equation of the train-like vehicle is established by using the "whole method".The derivation of the differential equation of motion provides a mathematical theoretical basis for the establishment of the state space model of the vehicle and the construction of the trailer's coordinated active steering controllerSummarize the selection of the dr-iving lateral stability evaluation index of multi-unit train-like vehicle in domestic and abroad research.The instability phenomenon in the operation process are listed.Using the virtual prototype model of the vehicle established by Adams/Car,the driving stability open-loop simulation is carried out under typical working conditions such as steering wheel step input and single lane change,thus the unstable form existing in the driving process of the vehicle is clarified.According to the established linear simplified mathematical model of the train-like vehicle,a number of evaluation indexes including the lateral velocity and the yaw rate of the tractor are selected as the state variables,and the state space equation of the vehicle is established.The principle of LQR linear quadratic control is analyzed and deduced in detail.The active steering control system of trailers is built in Matlab/Simulink,and the closed-loop control joint simulation under typical working conditions is combined with the virtual prototype model of train-like vehicleBy co-simulation under the typical conditions of " step input" and "single lane change",the results show that:the trailers active steering control method based on LQR principle can perform real-time control calculation by acquiring the state variables of the whole vehicle,output the rear three corners of the trailer tires,control the steering of each trailer,and make the yaw rate and lateral velocity of each vehicle unit and other evaluation indicators quickly reaches to steady state,reduces the amplitude of the side-slip angle and the articulation angle and the deviation of the running track of each tire,effectively suppresses the fluctuation phenomenon of each evaluation index during the operation,and effectively improves the overall driving stability of the train-like vehicle.