Vehicle 3 Dimentional Stability Control Based On Differential Braking

With the higher demand of vehicle safety,vehicle active safety technologies have been the research topic in recent years.Vehicle active safety technologies include Anti-lock Brake System(ABS),Traction Control System(TCS),Electronic Stability Control(ESC)system based on Direct Yaw moment Control(DYC),Active Front wheel Steering(AFS),Autonomous Emergency Braking(AEB)and so on.When amount of active safety technologies are applied on vehicle,the coordination control between different systems should be considered for potential influences or conflictions may arise inevitablely.This work mainly concentrates on the combined control of vehicle lateral stability and anti-rollover control based on differential braking.Variable time delays exist between the driver's inputs and the responses of the vehicle dynamic states during a critical steering course.Due to the delay of active brake actuators,a side-slip or a rollover may occur even to a vehicle with a traditional stability control system.In addition,the unnecessary intervention of rollover prevention controller may deteriorate yaw stability of a vehicle in these situations.To mitigate adverse effect of time delay on vehicle stability control and to realize coordinated stability control,a novel 3-Dimentional Dynamic Stability Controller(3DDSC)is designed for yaw stability control,yaw-roll stability control and rollover prevention control.The framework consists of an upper controller,a medium MPC controller and a lower controller.A nonlinear vehicle model is used in the upper controller to predict the vehicle's future states including yaw rate,side-slip angle and Load Transfer Ratio of vehicle and to determine the control mode and the related controllable areas with active brake method.Then model predictive control(MPC)is used in the medium controller to calculate the desired tire forces of four wheels under the constraints of the given controllable area;then the desired tire forces are realized by a lower hydraulic pressure controller.The proposed 3DDSC is evaluated with a CarSim-MATLAB co-simulation and Hardware-in-the-Loop simulation.The results show that 3DDSC can achieve a seamless integration of lateral stability and rollover prevention in complicated steering maneuvers.