Integrated Active Steering And Yaw Moment Control For Improving Vehicle Handling And Stability

An advanced control strategy is proposed to improve vehicle handling and stability by integrating Active Steering with Yaw Moment control. On the base of nonlinear tire model and one point preview-follower optimal curvature driver model, the vehicle dynamic model is established using the Newton's second law.Within the linear range of tire characteristics, the response of yaw-rate is improved by Active Front Steering (AFS) controller designed by the Sliding Mode theory. Based on the Optimal Control theory, the Direct Yaw Moment (DYC) controller is designed. The controller makes the vehicle follow the desired vehicle dynamic model designed by side-slip angle regulating feed forward and the state feedback of both yaw rate and side-slip angle. The integration of AFS and DYC is considered to improve the linear open–loop vehicle handling and stability.Within the nonlinear range of the characteristics, a reference stable region is designed in the phase plane for vehicle sideslipβand its velocityβand the stable boundary is determined with the two lines proximately. The yaw moment demand is calculated by the PI control theory. The controlling variable is the distance between the vehicle's state to the stable boundary in theβ-βphase plane. The Variable Torque Distribution (VTD) controller is designed by the driving torque difference between left and right sides of the same axle which is translated from the yaw moment demand.The integrated controller—AFS+VTD controller is designed and the stimulating research on the nonlinear open-loop vehicle handling and stability on the different adhesive coefficients with the AFS+VTD controller is done, as well as the path tracking ability of the nonlinear close-loop vehicle with the double lane change input. The computer stimulating result shows that the vehicle handling and stability are largely improved by the integrated controller of Active Steering with Yaw Moment control.