Estimation of Road Friction Coefficient Based on the Brush Model(<Special Issue>D & D 2008)

Abstract

The present paper discusses the estimation of the road friction coefficient based on the brush model. This popular tire model is reanalyzed beginning from the conventional simple physical model, and intrinsic expressions are derived. The grip margin, which is defined as the residual tire force normalized by the radius of friction circle, can be estimated using three components of the tire forces and the self-aligning torque. A cubic equation is obtained as a grip margin equation for the isotropic model. The anisotropic model yields a quintic equation. The solutions of these equations are approximated by Chebyshev polynomials. The estimation method is verified by numerical simulations using CarSim, which is a popular vehicle simulation software application. The estimated friction coefficients agree well with the assumed values for the cases of smaller grip margins, especially under lower-friction conditions.