Research On Active Steering And Yaw Moment Control Of Five-axle Vehicle

At present,with the promotion of economic development and objective demand,multi-axle automobile develops rapidly by virtue of the advantages of economy and efficiency,and has a position and role that cannot be ignored.Compared with traditional four-wheel vehicles,multi-axle vehicles often undertake many special tasks.However,due to its large mass,long wheelbase,high center of mass characteristics,resulting in frequent safety accidents,but also caused many people to pay attention to its safety performance,especially in the road conditions are poor,fast speed,easy to happen sideslip,tail swing and other instability phenomenon.In order to improve the lateral stability of five-axle vehicles in steering,the research work of this paper is detailed as follows:(1)Research on dynamic model of five axle-vehicle.Firstly,based on trucksim and Simulink,a five-axle vehicle dynamic model is established,including the design of structural parameters of each part of the vehicle in trucksim software and the derivation of two degree of freedom model formula.At the same time,the input and output interface of the joint simulation of trucksim and Simulink is defined.The accuracy of the control strategy is verified by comparison under specific conditions,which provides a theoretical reference model for the subsequent control strategy design;(2)Research on active steering control of five-axle vehicle.Three steering modes of front axle steering,zero centroid sideslip proportional control of all-wheel steering and proportional feedforward +LQR feedback optimal control were simulated in Matlab/Simulink.Trucksim/Simulink co-simulation results show that the designed proportional feedforward +LQR feedback optimal control improves the flexibility of low-speed steering and the stability of medium-high speed steering;(3)Research on direct yaw moment control of five-axle vehicle.The direct yaw moment controller is designed with the layered control system,and the fuzzy PID controller is used in the upper layer to obtain the additional yaw moment needed to keep the vehicle in a stable running state.Based on the stability analysis of the vehicle,the braking and driving wheel rules are reasonably formulated by the torque distribution controller at the lower level,and the calculated braking and driving moments are input into Truck Sim,so that the actual yaw velocity can track the expected yaw velocity.The Trucksim/Simulink co-simulation results show that the proposed direct yaw torque control strategy can effectively improve the steering stability of the vehicle under the extreme conditions.