A robust adaptive wheel-slip controller for antilock brake system

Although ABS has been widely spread on the commercial market for twenty years, throughgoing investigations with rigorous theoretical background have been lacking in the automotive literature. The control strategies of commercial ABS are mostly based on table rules to be calibrated through various experiments and tests, and the system dynamics cannot be effectively considered in the controller design. Due to the challenges in the automobile industry it is desired to develop a technique which still enhances the control performance and robustness with respect to various vehicle types and environment conditions. Motivated by these goals, a robust adaptive control algorithm is developed in this work. The proof of asymptotic stability is based on the Lyapunov method. The objective of such control is to maximize the tire friction under the assumption of knowing the optimal value of target slip. It is shown that, without any prior knowledge of the tire force and system parameters, the slip error is bound to converge to zero asymptotically. The robustness of the control system with respect to variation of the system parameters is guaranteed. The brake dynamic system to be controlled includes mechanical motion equations and the hydraulic circuit equations. A two-level control scheme is applied for the controller design, which considers the both parts separately