Fuzzy-Logic-Based Controller Design for Four-wheel-drive Electric Vehicle Yaw Stability Enhancement

Vehicle yaw stability enhancement controller for four-wheel-drive electric vehicle is proposed in this paper based on the fuzzy logic control technique. Brake differential control is used to stabilize vehicle yaw motion significantly. However, the forces between road and tires are not utilized effectively enough. As four motors are mounted in the four wheels individually to drive the vehicle, the four-wheel-drive electric vehicle has great advantage to use the tire traction and braking forces to generate active yaw moment for stabilizing vehicle motion. However it is more complex to allocate the desired yaw moment to over-actuators. So the control law for fuzzy logic controller is investigated based on the vehicle dynamic analysis. Simulation performance is evaluated in the CarMaker® virtual environment including driver model and road model. And the simulation results have shown that the design control law and fuzzy logic controller can enhance the yaw stability of the vehicle significantly, especially on the low friction road.