Research On Stability Control Of Electric Vehicle With Hub Motor Based On Electro-Hydraulic Coordinated Control

In the situation of global energy shortage and serious environmental pollution,the development of the automobile industry is facing severe challenges.Energy-saving,environmental protection,safety has become an emerging direction of automotive development.The hub-motor-driven electric vehicle is widely used in the research of the dynamic performance and stability of electric vehicles due to its unique structural advantages and performance characteristics.In this paper,four wheel hub motor drive electric vehicle as the research object,study of horizontal pendulum of the vehicle stability control problem,in view of the insufficiency of the motor torque output,coordinated control motor,hydraulic system,fully consider various constraint conditions,according to the response characteristics of the lower actuator design corresponding coordination,attach the upper controller obtained yawing moment control quantity between round optimization allocation,such as improve lateral stability when the car driving ability.Mainly carried out the following aspects of research:Firstly,aiming at the four-wheel hub-motor electric vehicle studied in this paper,the modular modeling idea is adopted to conduct the body dynamics modeling,and the tire and tire rotation dynamics model,motor model and hydraulic model are built.The precision and effectiveness of the vehicle dynamics model are verified by comparing with the co-simulation of the same parameter model in Carsim software.Then,the yaw stability controller is designed with hierarchical control structure.With linear two degrees of freedom vehicle model as reference model,select horizontal pendulum angular velocity and mass center side-slip Angle as control variable,fully considering the coupling relationship between them,the upper controller based on sliding mode control method to calculate the additional yawing moment,maintain the vehicle steady-state based on PI control theory for vehicle longitudinal motion tracking,tracking target speed required for the total longitudinal force are obtained.Utilization rate of the lower controller to minimize tire sum of squares as the optimization goal,using the weighted least square method to optimize a four wheel torque distribution,considering the actuators constraints and road adhesion conditions and related factors,the coordination of the motor and hydraulic system are studied to improve the stability of the vehicle,the specific policy is: to rely on the motor with torque output,when the motor torque output is insufficient,uses hydraulic system to compensate the output torque.Finally,in order to verify the effectiveness and real-time performance of the proposed control strategy,the open-loop control system was built in the dynamics simulation Matlab/Simulink,and the single-period sinusoidal steering and sinusoidal delay conditions were selected for offline simulation experiments.At the same time,based on the NI hardware in the ring test platform,the designed control system is imported into the hardware controller,and the corresponding conditions are set for the hardware in the ring simulation experiment.