Longitudinal Tire Force Estimation With Unknown Input Observer

This paper presents the development of a longitudinal tire force estimation algorithm. Rather than using highly nonlinear tire-road friction models, we propose a decentralized estimation algorithm which treats the longitudinal tire force of the individual wheel as an unknown input signal for the one-DOF wheel dynamic model. Two types of unknown input observers are designed to estimate the longitudinal tire force based on the wheel speed measurement in this study. To make the estimated tire force signals also satisfy the longitudinal dynamic model of the vehicle, the estimation results of the unknown input observer are integrated with the longitudinal acceleration measurement by using a projection method.Copyright © 2012 by ASME and General Motors