SLIP-BASED TIRE ROAD FRICTION ESTIMATION

An approach to estimate the tire-road friction during normal drive usi ng only the wheel slip, that is, the relative difference in wheel velo cities, is presented. The driver can be informed about the maximum fri ction force and be alarmed for sudden changes. Friction-related parame ters are estimated using only signals from standard sensors in a moder n car. An adaptive estimator is presented for a model linear in parame ters, which is designed to work for periods of poor excitation. errors in variables, simultaneous slow and fast parameter drifts and abrupt changes. The physical relation between these parameters and the maxima l friction force is determined from extensive field trials using a Vol vo 850 GLT as a test car. (C) 1997 Elsevier Science Ltd.