Road surface frictional coefficient estimation device, driving force distribution control device and four-wheel-drive vehicle

摘要

A road surface frictional coefficient estimation device includes: a first straight travel determination unit configured to determine whether or not a vehicle travels straight based on a rotational speed difference between a plurality of wheels of the vehicle; a second straight travel determination unit configured to determine whether or not the vehicle travels straight based on a steering angle of the vehicle; a selection unit configured to select one of determination results of the first straight travel determination unit and the second straight travel determination unit; and a frictional coefficient estimation unit configured to estimate a frictional coefficient of a road surface on which the vehicle travels when the one of the determination results selected by the selection unit indicates that the vehicle travels straight.