Stability Control And Optimal Torque Distribution Of In-wheel Motor Electric Vehicle

Safety,energy saving,and environmental protection are the eternal development themes of automobiles,which promote the rapid development of new energy vehicles.In-wheel motor electric vehicles(IMEV)are electric vehicles directly driven by in-wheel motors,because of their fast response speed and flexible path tracking.It has become an important research topic for the future development of pure electric vehicles.For modern vehicles,safety is one of its most important properties.In-wheel motor electric vehicles have huge potential to improve vehicle performance.The distribution of the torque of each wheel and maintaining the lateral stability of the in-wheel motor electric vehicle is one of the key issues,which can effectively prevent the occurrence of dangerous situations such as sideslip and rollover.This paper takes the in-wheel motor electric vehicle as the research object,focuses on the vehicle’s lateral stability control,and considers the optimal distribution of wheel torque while the vehicle remains stable.The main work is as follows:First,determine the degree of freedom of the vehicle model according to the kinematic characteristics that affect the lateral stability of the vehicle,build a seven-degree-of-freedom vehicle model including vehicle dynamics model,tire model,and wheel dynamics model,and build external driving for in-wheel electric vehicles.Operator model and the in-wheel motor parameter matching and model establishment.Finally,the in-wheel motor electric vehicle model is built using the Carsim and Simulink co-simulation platform and the accuracy of the model is verified.Secondly,this paper adopts a hierarchical control structure,the upper layer is the motion tracking layer,analyzes the factors that affect the stability of the vehicle and the control mechanism,designs the vehicle stability judgment controller.According to the actual steering and driving conditions of the vehicle,the direct yaw moment controller of multi-objective state feedback controller is proposed considering the uncertainty of vehicle speed and saturation of actuators.In order to make the vehicle still have good handling stability on low-adhesion roads,a slip rate controller based on fuzzy PID is designed.The simulation platform is used to verify the effect of the designed stability controller.Finally,the lower torque distribution layer reasonably distributes the drive adjustment torque obtained by the upper controller for speed maintenance,the slip rate torque,and the additional yaw moment required by the stability controller.The distribution method is based on the average distribution,dynamic load distribution and quadratic programming problem.The result of the solution is assigned.The built-up Carsim and Simulink simulation platforms are used to verify the stability control strategy of in-wheel motor electric vehicles.The results show that the torque optimal distribution method designed in this paper has better control effects than average distribution and dynamic load distribution,and significantly improves the vehicle’s lateral direction stability.