Four-wheel steering motor vehicle

Abstract

A four-wheel steering motor vehicle adapted to prevent a steering ratio of the rear wheels to the front wheels from varying at the time of sudden braking when the pressure of a brake liquid is reduced by an antilock brake unit. This vehicle includes a front wheel steering unit for steering the front wheels in accordance with angular movement of a steering wheel, a rear wheel steering unit for steering the rear wheels, steering control unit for determining a target steering angle of the respective rear wheels based on a vehicle speed and a front wheel steering angle and for controlling the rear wheel steering unit in such a manner that the rear wheel steering unit steers the rear wheel until a rear wheel steering angle reaches the target value, an antilock brake unit for calculating a slip coefficient of each wheel based on a sensed rotating speed of each wheel and for reducing the pressure of a brake liquid being supplied to a brake of the individual wheel when the slip coefficient of the wheel exceeds a predetermined value. The steering control unit controls the rear wheel steering unit so as to substantially prevent the rear wheel steering angle from varying when the pressure to the brake liquid is reduced by the antilock brake unit.