Study on a new four-wheel-steering control method at low speeds-front-end path memorizing method

There are demands for improved vehicle stability in high speed driving. This problem can be overcome by using an opposite-direction-proportional four-wheel-steering control system, which turns the rear wheels in the opposite direction of the front wheels at low speed to improve maneuverability. A study was made of a new four-wheel-steering control method based on opposite-direction steering of the rear wheels using a procedure whereby the wheelbase is reduced in an equivalent manner. With this method, the front-end path is memorized and that information is used to determine the limits of opposite-direction steering of the rear wheels so that the rear end of the vehicle is always kept within the front-end path. The authors explain the control method and hardware configuration. The results of driving tests are then presented to show the effectiveness of this four-wheel-steering control method at low speeds