A target resultant force to be applied to a vehicle body is calculated,
the magnitude of a critical friction circle of each wheel is estimated,
and a critical resultant force is estimated from the estimated magnitude
of the critical friction circle. Subsequently, a ratio of the target
resultant force to a critical resultant force is set as an effective road
friction, and the magnitude of a tire force is set by using the magnitude
of the critical friction circle and the effective road friction. The
direction of the tire force of each wheel to be controlled is set based
on the sum of products, which are calculated for all other wheels, of a
distance from the position of the wheel to be controlled to the position
of the other wheel in a direction of the resultant force, and the
magnitude of the tire force of the other wheel. Cooperative control of
steering and braking or steering and driving of each wheel to be
controlled is performed based on the magnitude and direction of the tire
force which have been set.