This paper presents a method for estimating the maximum lateral tire-road friction coefficient and wheel side slip angle based on the pneumatic trail information that exhibits unique characteristics according to the road surface conditions. The high sensitivity of the pneumatic trail for the wheel side slip angle enables the proposed observer to detect the peak tire-road friction coefficient in low slip regions. The conventional method that is highly dependent on the tire model has drawbacks due to model uncertainty. In order to overcome these shortcomings, the proposed method minimizes the use of existing tire models. In addition, traction force is also considered in this paper using a correction factor. The estimation results are obtained recursively under the persistent excitation condition. A simulation is conducted first in order to verify the performance of the proposed method using a combination of the Carsim and Matlab & Simulink. Then, vehicle experiments are conducted on a proving ground in order to verify the feasibility of the proposed method. The verification results reveal that the early detection of the maximum tire-road friction coefficient is possible with less excitation signals than the conventional methods.
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