Gain Scheduled Active Steering Control Based on a Parametric Bicycle Model

This paper presents a gain scheduled active steering control design method to preserve vehicle stability in extreme handling situations. It is shown that instead of the classical linear tire model based on expressing cornering force proportional to tire sideslip angle, a simple rational model with validity extending beyond the linear regime of the tire may be considered. This results in a new formulation of the bicycle model in which tire sideslip angles and vehicle forward speed appear as time-varying parameters. Such a model happens to be useful in the design of controllers scheduled by tire sideslip angles: after having expressed the parametric bicycle model in the parametric descriptor form, a gain scheduled active steering controller is designed in this study to improve vehicle handling at "large" driver commanded steering angles. Simulations reveal the efficiency of the selected modeling and controller design methodology in enhancing vehicle handling capacity during cornering on roads with high and low adhesion coefficient.