Research On DYC Of Independent Drive Electric Vehicle With The Time-varying Delays

The four-motor independent drive that is adopted in independent driving EV,can achieve flexible torque distribution,in order to provide a favorable basis for the realization of the control of handling stability.But the four-motor coordinated control has a high demand for real time and certainty of vehicle bus information transmission.The network induced delay during the information transmission on the current vehicle bus will make the independent drive electric vehicle handling stability worse,or even instability.So enhancing the robustness of control system and solving the dynamic control chattering problem caused by the network induced delay is of great significance for improving the handing stability and safety of the independent driving electric vehicle,which can be realized by establishing the networked control model of vehicle handling stability,analyzing the mechanism of network induced time delay and its influence on the control of vehicle handing stability and then designing the variable parameter sliding mode controller based on fuzzy inference.In this paper,we study the handing stability of the independent driving electric vehicle based on the vehicle bus.The main research contents and results are as follows:(1)The closed-loop simulation platform of "human-vehicle" is established,which includes eight degree of freedom vehicle model,motor and transmission system model,wheel dynamics model,tire model and driver model.And the simulation platform can simulate the dynamic response of independent drive electric vehicle,and meet the requirements of simulation analysis.(2)Adopting the hierarchical control structure to design control strategy of handing stability and taking the linear two degree of freedom vehicle model for reference.Using control strategy of sliding mode variable structure to calculate the required steering yaw moment on the upper layer of motion tracking.Using the method of average torque distribution on the lower layer which also means the torque distribution layer.By simulation in condition of step transient input to steering angle,double lane change and snake cornering,the effectiveness of the control strategy has been verified.(3)Establishing the networked control model of handling stability of independent drive electric vehicle based on the vehicle bus and analyzing the mechanism of induced delay on vehicle bus and its effect on the control performance.Simulation verified that network delay may cause chattering phenomenon in vehicle dynamics control system,which would make the handing stability performance of independent drive electric vehicle worse.(4)Three different variable-parameter sliding mode controllers based on fuzzy inference have been designed,in which network delay,switching function,and input of control variables were taken as the basis for judging the thickness of boundary layer in sliding mode control.The chattering phenomenon of control system caused by the network delay and high gain constant reaching law were eliminated,and meanwhile,the output torque curve of the motor was smoother and the robustness of the DYC system is stronger.