Vehicle Lateral Control and Yaw Stability Control through Differential Braking

This paper examines the effectiveness of a brake-by-wire system with the uses of differential brake torque for lateral control and yaw stability control in the context of Intelligent Vehicle Highway Systems. Differential braking easily realized by the brake-by-wire system can generate the vehicle yaw moment. The resulting yaw moment affects vehicle lateral position and yaw rate, thereby providing a limited steering function. The steering function achieved through BBW system can then be used to control lateral position in an unintended road departure system. A 7-DOF model is developed to capture the vehicle longitudinal, lateral and yaw motion, and the other four degrees of motion representing the wheel dynamics. Since the 7-DOF model is rather complicated for controller design, a linearized vehicle model is presented for the explanation of the idea of differential braking and for the control design. A fuzzy logic controller is developed to explore the feasibility and capability of BBW systems for lateral control and yaw stability control. Simulation results on the nonlinear vehicle model are used to illustrate the effectiveness of the fuzzy logic control approach for lateral control and yaw stability control with differential braking.