DEVICE AND METHOD FOR ESTIMATING TREAD FRICTION STATE OF VEHICLE

PROBLEM TO BE SOLVED: To provide a device and method for properly estimating the grip characteristic of a tire. SOLUTION: A vehicle includes: a tangential gradient correlation map including a correction between a reference value ratio that is a ratio of tire force and slippage which are obtained on a reference road surface by a reference tire and a tangential inclination in the reference value ratio of a continuous characteristic line where the correlation between these tire force and slippage is established; a tire grip state arithmetic unit 46 which obtains a tangential inclination corresponding to the reference value ratio while taking a detection value ratio detected based on detected current tire force and current slippage as the reference value ratio; and a map linear area Cp value estimation unit 49 and a correction unit 50 which correct the tangential gradient correlation map based on a correction factor, the correction factor being a ratio of the detection value ratio of detected tire force and slippage in an area where the correlation between these tire force and slippage has a linear correlation to a reference value ratio of the tire force and slippage in the tangential gradient correlation map in an area where the correlation between these tire force and slippage has a linear correlation. COPYRIGHT: (C)2010,JPO&INPIT