Research On Vehicle Stability Technology Of Electric Vehicle Based On Dual-rate Sampling State Feedback Control

The problem of vehicle security has always been the focus of people's attention.With the development of automotive electronic control technology and the renewal of automobile control theories,modern automobiles will definitely become more safe,intelligent and environmentally friendly.Electric vehicle represents more energy-saving and environmental protection,but it also faces many technical bottlenecks.For electric vehicle driven by hub motors,as the motor and the wheels are bundled together,the quality of a single wheel is very large.Although it is more flexible in driving,there is still much room for economic and stability control.It is similar to the traditional vehicle stability control that hub motor electric vehicle can also control vehicle stability by providing additional yaw moment.However,because of the natural advantages of hub motor electric vehicle,we can apply four-wheel torque distribution control to hub motor electric vehicle better.At the same time,the sampling control system technology has been constantly mature and improved.In this paper,we will use the state feedback control of dual-rate sampling control system combined with the torque distribution of four in-wheel motors to control the stability of the vehicle.The main research contents are as follows:(1)By summarizing the research on vehicle stability control by experts and scholars,the control variables and control scheme were determined and the seven-degree-of-freedom model and the ideal vehicle tracking model were established,providing the model function and scheme function for the later controller design.(2)Yaw rate and sideslip angle are important control variables to stability control.As to the problem of sampling period asynchronization of yaw rate and sideslip angle,we propose a dual-rate sampling control strategy,design a dual-rate sampling controller and prove the Lyapunov stability of the controller.Dual-rate sampling controller obtains real-time additional yaw moment through dual-rate sampling control system.Dual-rate sampling control system is also the upper control system of vehicle stability control.(3)According to the yaw moment of stability control determined by upper control system and different driving conditions of vehicles,we design two moment allocation strategies based on stability and economy as lower controller control to ensure stable driving of vehicles.We determine the driving condition of the vehicle according to the yaw rate.The optimal solution of four wheel torques is obtained by the control algorithm based on weighted least square method.(4)software simulation based on dual-rate sampling controller and four-wheel moment distribution system in Simulink is carried out,which is compared with the ideal value obtained by ideal vehicle tracking model.Based on the co-simulation(Carsim and Simulink)and comparing with the control model of Carsim,the performance of designed controller was achieved.