Road surface friction state estimating apparatus and method thereof

摘要

A SAT estimating portion supplies a grip degree estimating portion with the estimated SAT value. A summing device sums a front wheel slip angle on which high pass filter processing has been performed and a front wheel slip angle on which low pass filter processing has been performed so as to obtain an integrated slip angle. A grip degree estimating portion estimates a grip degree of a tire, by calculating a SAT reference value which is based on the integrated slip angle, and calculating a ratio between the SAT reference value and the estimated SAT value. A road surface mu value estimating portion estimates a road surface mu value when the grip degree becomes equal to or lower than a reference value.