Estimation of Friction Levels Between Tire and Road

This study relates to an apparatus and a method for determining the road friction levels between the tire of a car and the road surface by using rotational information from the four tires. The theory to determine the road friction is based on the characteristics of the tire μ-s curve. By detecting the slope of the tire μ-s curve at a very small change of slip ratio, a determination of the slip level is achieved during normal driving conditions.