Estimation of the maximum tire-road friction coefficient

We develop and test a "slip-based" method to estimate the maximum available tire-road friction during braking. The method is based on the hypothesis that the low-slip, low-mu, parts of the slip curve used during normal driving can indicate the maximum tire-road friction coefficient, We find support for this hypothesis in the literature and through experiments. The friction estimation algorithm uses data from short braking maneuvers with peak accelerations of 3.9 m/s(2) to classify the road surface as either dry (mu(max) approximate to 1) or lubricated (mu(max)approximate to0.6) . Significant measurement noise makes it difficult to detect the subtle affect being measured, leading to a misclassification rate of 20%.