AFS and DYC Extension Coordinated Control Under Extreme Condition
The integrated control of active front steering(AFS)and direct yaw moment control(DYC)can improve the handling and stability of commercial trucks.Because the effect of active front wheel steering is limited in the nonlinear region of tire,the con-trol effect of simple superposition of active front wheel steering and direct yaw moment control may not meet the expectations,so the extension coordinated control system is designed in this paper.The system is divided into upper,middle and lower three layers,the upper layer is AFS and DYC coordination switching control layer.The critical steering angle of the front wheel was obtained by ex-periment,and the steady-state sideslip angle under the critical steering angle was backcalculated according to the linear two-de-gree-of-freedom vehicle model.The phase plane diagram was partitioned according to the actual vehicle sideslip angle and its ve-locity phase plane stability region,and three different coordinated control strategies were designed.In the middle layer,AFS and DYC sliding mode controllers are designed based on the exponential reaching law,which can obtain the additional steering angle and yaw moment of the front wheel;And that additional yaw moment is distribute by the lower lay controller according to the real-time state of the vehicle.A co-simulation platform was established by TruckSim and Matlab/Simulink,and the extension coordinat-ed control system was simulated and verified under extreme conditions.The simulation results show that the optimal extension coor-dination strategy is obtained.The coordination control makes up for the defects of AFS/DYC single control,and can ensure the vehi-cle handling stability and driving safety.
Handling StabilityActive Front Wheel SteeringDirect Yaw MomentPhase PlaneFront Wheel Criti-cal AngleExtension Coordinated Control
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