To provide a detector, for the coefficient of friction of a road surface, by which the coefficient of friction of the running road surface for a vehicle can be detected with good accuracy.
On the basis of a steering angle and a vehicle speed, a target yaw rate and a target transverse acceleration (a target transverse G) are set. When an actual yaw rate is too small with reference to the target yaw rate (S 495: YES) and when an actual transverse G is not too large with reference to the target G (S 500: NO), it is judged that front-wheel tires reaches their limit (S 505, S 530: YES). On the basis of the gripping force (the front gripping force) of the front-wheel tires at their time to a load (an FR wheel load + an FL wheel load), the coefficient of friction (the estimation μ) of a toad surface is computed (S 535, S 540). In addition, when the actual yaw rate is too large with reference to the target yaw rate (S 515: YES), it is judged that rear-wheel tires reached their limit. On the basis of the ratio of the gripping force (the rear gripping force) of rear-wheel tires at this time, to a load (an FR wheel load + an FL wheel load), the estimation μ is computed (S550, S 555).
SUZUKI MOTOJI
IDO TOSHIYUKI
