Research On Lane Keeping And Stability Control Of Intelligent Vehicle

The integration of various high and new technologies in intelligent vehicles is the development direction of vehicles in the future,as well as the technical update of the traditional vehicle industry.As one of the core technologies of intelligent vehicles,lane keeping system is used to control vehicles to drive according to the expected lane center line and reduce traffic accidents caused by lane departure due to negligence and fatigue driving.In recent years,lane keeping control has been widely studied and achieved advanced results.However,the traditional lane keeping control can track the lane center line accurately and keep the vehicle stability to a certain extent,but it still can not meet the stability requirements of vehicle driving.Therefore,this paper proposes a hierarchical control strategy which integrates the rear wheel angle compensation and lane keeping,so as to achieve lane keeping accurately and improve vehicle stability.Firstly,taking the whole vehicle as the research object,according to the vehicle dynamics and kinematics characteristics,the linear two degree of freedom model of the vehicle is derived,and the system state equation is derived.The magic formula tire model is used to describe the tire characteristics and carry out simulation verification,which lays the foundation for the subsequent layered control.Secondly,aiming at lane tracking problem in lane keeping system,this paper designs lane keeping controller as upper controller based on model predictive control,and establishes a two degree of freedom linear model based on lane center line as lane keeping predictive model combining with lane center line preview model.By controlling the minimum lateral position deviation of the vehicle,the wheel angle and yaw rate are constrained in the process of vehicle driving,and the relaxation factor is introduced.At the same time,considering the stability requirements of the vehicle driving,the optimal front wheel angle is obtained by combining the constraint conditions and the optimization objective function.In different road environment and working conditions,the algorithm proposed in this paper is simulated and analyzed to verify the feasibility and effectiveness of the control method.Finally,in order to improve the stability of the vehicle on the low adhesion road,the steering characteristics and control strategy of the four-wheel steering intelligent vehicle are studied.The front wheel angle feedforward yaw rate feedback rear wheel angle compensation controller based on the optimal tracking control is designed as the lower controller.The front wheel angle calculated by the upper controller is used as the input parameter for feedforward control,the actual yaw rate of the vehicle is used for feedback control,and the optimal rear wheel compensation angle is obtained through the optimal tracking control theory.The simulation results show that the designed layered control system can effectively achieve lane keeping and vehicle stability control under different adhesion pavement coefficients.