Parameter identification and adaptive control for improved vehicle yaw stability performance

Applications of automatic steering constitute an active research field within automotive control systems. The steering performance of a vehicle can be evaluated in terms of the extent to which it is capable of following demanding road trajectories. Conventional yaw stability controllers used to restrict the extreme understeering or oversteering vehicle behavior are inevitably challenged by uncertain vehicle dynamics. We develop a simplified vehicle yaw dynamics model subject to steering angle rate constraints and introduce an adaptive yaw control design methodology in order to address possible design conflicts between steering angle rate constraints and achievable steering performance of the vehicle. Our parameter estimation scheme and adaptive control strategy can be employed in automatic steering applications with the promise of improved yaw stability performance in the presence of uncertain tire cornering stiffnesses and unknown road adhesion factor.