DEVICE FOR ESTIMATING ROAD SURFACE FRICTION STATE

摘要

PROBLEM TO BE SOLVED: To improve an estimation speed of a road surface friction state and to restrict dispersion of the estimated values without increasing costs. SOLUTION: A pretreatment filter 2 selects a wheel speed vibrationΔω1 from a wheel speedω1 detected by a wheel speed sensor 1. A transfer function identifying circuit 3 identifies a transfer function by using a forgetting coefficientρon the basis of the wheel speed vibrationΔω1. A correlation coefficient calculating circuit 4 calculates a correlation coefficientσby using the wheel speed vibrationΔω1 from the filter 2 for setting the forgetting coefficientρto be used for the transfer function identifying circuit 3 according to the calculated correlation coefficientσ. Aμ-gradient, calculating circuit 5 estimates aμ-gradient on the basis of the identified transfer function.