In the case that a brake controller is installed to a 4 wheel driven
vehicle, braking force control should be carried out effectively enough so
that running stability of the vehicle can be up-graded at cornering. The
brake controller 40 calculates differential value of aimed yaw rate,
differential value of predicted yaw rate on low friction road and
deflection of the two differential values. And also it calculates
deflection of real yaw rate and aimed yaw rate. Then the brake controller
40 determines aimed braking force and applies the aimed braking force to a
selected wheel to carry out braking control. The torque distribution
controller 70 receives control parameters and signals of status of brake
control and carries out torque distribution control based on the
parameters and signals through the hydraulic multi-plate clutch 21. The
hydraulic multi-plate clutch 21 is so controlled with certain weak
engaging force as to make each wheel rotate freely, when braking control
is carried out by applying braking force to a selected wheel. Thus the
brake controller 40 can perform as aimed.