Intelligent Real-Time 4WD Control Development to Improve Vehicle Traction and Handling Performance

The transfer case adjusts the vehicle axle torque distribution by controlling the transfer case clutch torque, thereby improving vehicle traction and stability. This paper proposed an intelligent real-time 4WD control method, consist of intelligent preload control, active yaw control and slip control. When the vehicle is under stable driving conditions, the transfer case clutch torque is set to zero to obtain good economy performance. When the vehicle is under acceleration, climbing, slippery road or off-road conditions, the transfer case clutch preload torque control is large to achieve strong 4WD traction ability. In steering conditions, the transfer case clutch torque is adjusted through active yaw control to improve the vehicle handling and stability. When one single axle has a tendency to slip, the proposed slip control can quickly engage the transfer case clutch to avoid single wheel slip and improve vehicle traction performance. Through the real vehicle verification, the proposed control strategy can significantly improve the vehicle traction and handling performance.