Optimal design of a non-linear controller for anti-lock braking system

The most effective chassis control system for improving vehicle safety during severe braking is anti-lock braking system (ABS). In this paper, a nonlinear optimal controller is analytically designed for ABS by the prediction of the wheel slip response from a continuous nonlinear vehicle dynamics model. A new reference model for the wheel slip, which considers the effects of variations of tire normal load and tire/road condition, is proposed to be tracked by the controller. The main properties of the designed controller are evaluated and discussed by considering the important practical aspects of the slip control problem. The performed analysis along with the simulation results indicate that the designed controller with different special cases can successfully cope with the strong nonlinearity and realistic uncertainties existing in vehicle dynamics model. Meanwhile, a compromise between tracking accuracy and control energy can be easily made by the regulation of the weighting ratio, as a free parameter in the optimal control law. (C) 2012 Elsevier Ltd. All rights reserved.