PURPOSE: To ensure vehicle travel stability during deceleration in turning state by providing a change means for setting a threshold value smaller to initiate toe-in control, according to a handle steering angle increase in a steering device to steer a rear wheel in a toe-in direction at the time of deceleration.
CONSTITUTION: A four-wheel drive vehicle is equipped with a front wheel steering mechanism A having a steering mechanism C connected thereto, and a rear wheel steering mechanism B actuated with a drive means E. Also, the drive means E has a stepping motor 30 driven and controlled with a control unit 40. This control unit 40 obtains control values via input values from a speed sensor S1, a throttle position sensor S2 or the like, and controls right and left rear wheels for steering in a toe-in direction at the time of deceleration. In this case, toe-in control is caused to start, when the deceleration of the vehicle exceeds the predetermined threshold value. Furthermore, a threshold value to initiate the toe-in control is so set as to become smaller according to an increase in a steering angle, on the basis of the values of a handle steering angle and vehicle speed.
OMURA HIROSHI
UEDA KOJI
MISHIMA RITSUYA