Study On Motion Characteristics And Stability Control Of Vehicle With Flat Tire

In recent years,the number of road traffic accidents has increased due to the growing number of motor vehicles.Among them,accidents caused by flat tire have been on the rise.Particularly on highways,flat tire have resulted in a high fatality rate,causing significant losses in terms of personal safety and property.Therefore,this study focuses on investigating the motion characteristics and stability control of vehicles experiencing flat tire on highways.The main research consists of the following three parts:(1)Establishment of steady-state tire and vehicle models: Using the parameters of a 205/60R15(MF-Tyre v2020.1)tire and a C-type vehicle in the Carsim software,a steady-state tire model based on the "magic formula" is developed using the Matlab/Simulink toolbox.The model simulates the influence of tire slip ratio and lateral slip angle on longitudinal and lateral forces.Subsequently,an eight-degree-of-freedom vehicle dynamics model is constructed based on the tire model,incorporating a driver model to create a comprehensive vehicle model.Finally,a joint simulation environment combining Carsim and Simulink is utilized to conduct stability testing experiments on the vehicle model,comparing and analyzing the vehicle’s motion state with the Carsim automotive model to validate the rationality and reliability of the complete vehicle model.(2)Development of a modified "magic formula" flat tire model and blowout vehicle model:The mechanical characteristics of a blowout tire,including changes in vertical load,longitudinal and lateral forces,additional yaw moment induced by the blowout,and the impact of tire mechanical changes on the vehicle’s motion state,are analyzed and organized.Based on these changes,a modified "magic formula" flat tire model and blowout vehicle model are established.The correctness of the modified blowout model is validated through simulation analysis of the longitudinal slip and lateral characteristics of the flat tire model.Finally,simulation experiments are conducted on the blowout vehicle model to analyze the effects of flat tire under different operating conditions and positions,summarizing the variations in the vehicle’s motion characteristics and kinematic parameters.(3)Proposal of a blowout vehicle stability control strategy: Taking the yaw angular velocity and center of gravity lateral deviation of a two-degree-of-freedom ideal vehicle model as control objectives,an upper-level controller based on the sliding mode variable structure control method is developed.Criteria for determining vehicle stability and balancing the yaw moment error between the blowout vehicle model and the ideal model control objective are defined.Subsequently,a lower-level controller based on the differential braking method is employed to allocate and calculate the required wheel braking torques for achieving yaw moment balance under the current blowout condition.Finally,by integrating the blowout vehicle model with the upper and lower-level controllers,a blowout vehicle stability control model is established.Simulation experiments are performed on blowout vehicles under different conditions,such as straight-line driving and turning,to evaluate the proposed control strategy.The experimental results demonstrate that the designed blowout vehicle stability control strategy effectively improves the vehicle’s motion state,thereby providing assistance for safe vehicle operation.