The Study On Modeling And Simulation And Control Strategy Based On 4WS Of An Off-road Vehicle

With the continuous development of science and technology,the army applies differrent kinds of new technology to military off-road vehicle gradually.Four wheel steering technology can improve the handling stability of the vehicle at high speed and maneuverability at low speed.Because of the high requirements of equipment for military off-road vehicles,the four wheel steering technology has a good development opportunity.Firstly,the paper introduced background and significance of the research,summarizes the four wheel steering technology development and research situation,the four wheel steering vehicle control method,this paper expounds the main research work.Secondly,in this paper,the motion analysis and structural optimization of the front and rear double wishbone independent suspension are carried out.Based on ADAMS/Car software platform,the multi-body kinematics model of the front and rear double wishbone independent suspension was established by the software,kinematics simulation analysis,evaluation of the reasonableness of suspension data.and on the basis,the hard points coordinates of rear suspension were optimized.Then,the characteristics of the front wheel steering and four wheel steering are analyzed,and the vehicle model of the front wheel steering with two degrees of freedom is established.In the three degree of freedom of four wheel steering vehicle based on dynamic model,using the zero sideslip feedforward control strategy of the model simulation analysis.Considering the nonlinear characteristics of tire under the limit condition,the magic tire model is introduced.Finally,comparative analysis of the front and rear wheel proportional control,yaw rate proportional feedback control,feedforward and fuzzy yaw rate feedback control,feedforward and sideslip angle and yaw rate fuzzy control combined with four different strategies,and establish the corresponding control model in MATLAB/Simulink.The simulation test of four wheel steering vehicle is carried out with different control strategies.The simulation results show that the feedforward and sideslip angle and yaw rate feedback control combined with fuzzy strategy can better track the ideal steering model and improve the handling stability of off-road vehicle.