Research On Vehicle Lateral Stability Control Based On Model Predictive Control

The emergence of automobiles has completely changed the way people travel,and brought great convenience to us.However,the increasing number of automobiles has brought disaster to people.According to the Global Road Safety Status Report published by the World Health Organization in 2018,1.35 million people die annually from road traffic worldwide.In addition,research shows that 40% of the traffic accidents occurred at medium and high speed are related to the lateral stability of the vehicle.Therefore,it is of great significance to improve the lateral stability and driving safety of vehicles to reduce road traffic accidents and casualties.Active front steering(AFS)and direct yaw moment control(DYC)are important means to improve vehicle lateral stability.However,the active braking intervention of DYC will cause the longitudinal speed of the vehicle to decrease,which will affect the longitudinal dynamics and driving comfort of the vehicle.Different from DYC,AFS can improve the lateral stability of the vehicle without affecting the longitudinal dynamics and comfort through the active intervention of the steering system.It has been widely studied in recent years.Based on the existing research,this paper designs a new linear time-varying AFS control system based on the model predictive control method that takes into account the nonlinear change of tire force in the prediction horizon.It can effectively improve the real-time performance of the system,broaden the working range of AFS,and improve the lateral stability of the vehicle in the limit condition.With the development of intelligent and autonomous vehicles,active collision avoidance control has gradually become an important means to improve vehicle driving safety and reduce traffic accident injuries.AFS-based lateral collision avoidance control requires only a small steering intervention to produce sufficient yaw moment and lateral offset.Compared with the longitudinal collision avoidance control,the collision avoidance distance of lateral collision avoidance control is shorter under the limit conditions of high-speed and low adhesion road,which is favored by researchers.The tire force is often in the non-linear region in the limit condition,and the vehicle is prone to the danger of side slip during steering and collision avoidance.Therefore,this paper designs a steering collision avoidance controller that takes into account the prediction of tire state stiffness based on the model predictive control for the stability of the vehicle during steering avoidance in the limit condition.It can better balance the collision avoidance effect and driving stability of the vehicle in the limit conditions.When the tire lateral force is close to saturation,the control performance of AFS will approach the limit.But DYC can still use the longitudinal force to generate yaw moment to keep the vehicle stable at this time.Therefore,the integrated control of AFS and DYC can make full use of the advantages of the two to further improve the lateral stability of the vehicle.However,there is mutual interference and coupling between AFS and DYC on vehicle motion,and there is also mutual influence between tire lateral force and longitudinal force.Therefore,the control right distribution of steering and brake of integrated control of AFS and DYC has always been a research hotspot.In response to this research,this paper proposes a distribution method of tire longitudinal and lateral force that considers the equal reserve capacity of the tire,and and designs a holistic AFS and DYC integrated controller based on linear time-varying model predictive control,which can effectively solve the problem of motion interference and control right distribution between AFS and DYC,and further improve the lateral stability of the vehicle.