Nonlinear Estimation of Longitudinal Tire Slip Under Several Driving Conditions

This paper presents an effectively unbiased nonlinear estimation scheme which identifies tire longitudinal stiffness and effective radius using GPS and ABS wheelspeed sensors. This estimation strategy is then used to experimentally identify the longitudinal stiffness and effective radius of a summer tire and a winter tire under several different test conditions. The data clearly shows that there are several important parameters which govern tire longitudinal stiffness behavior in the low slip region. At a minimum, inflation pressure, tread depth, normal loading and temperature have a strong influence on longitudinal stiffness estimates; the change from dry to wet asphalt had the smallest effect on longitudinal stiffness estimates.