DEVICE FOR ESTIMATING FRICTIONAL CONDITION OF RAOD SURFACE

摘要

PROBLEM TO BE SOLVED: To provide an inexpensive device for estimating a frictional condition in a road surface. SOLUTION: A steering torque signal detected by a torque sensor 22 provide in an electric power steering device is input into a band-pass filter 30 to pass only a signal having about 40-50 Hz of frequency band. A damping coefficient of a secondary resonance model approximated to a suspension tire resonance model is identified based on a signal output from the band-pass filter 30 by an on-side identifying method, and a SAT gradient is estimated based on the identified damping coefficient.