Estimation and change detection of tire-road friction using the wheel slip

This paper describes some filtering and change detection problems in an approach to estimate the tire-road friction. The method is aimed to work during a normal drive using information from standard sensors only, and the driver is informed about the maximal friction force and warned for sudden changes. From a physical model of tire-road friction based on the so called wheel slip, a Kalman filter is constructed. To get a fast response to friction changes, some alternative change detectors are examined. We also describe the algorithm that has been implemented in real-time on a Volvo 850 and some of the results from extensive tests.