Four-Wheel Independent Steering (4WIS) System for Vehicle Handling Improvement by Active Rear Toe Control.

Abstract

This paper presents the enhancement of vehicle cornering stability through active and independent rear toe control. Because toe change in the rear wheel during high-speed turning maneuvers is an important factor influencing vehicle stability, the active rear toe control vehicle such as four-wheel steering(4WS)vehicle has been developed in past years. Especially, a toe in the rear outer wheel(bump side)plays a dominant role in cornering, hence the four-wheel independent steering(4WIS)system which selectively or simultaneously controls the rear wheels, could be suggested. In the proposed system, there are some advantages not only in energy consumption, but also in control responsiveness. The independent rear steering strategy using rear toe control scheme has been developed and its performances were evaluated with the ADAMS full vehicle model. Also, 4WIS system is compared to the conventional four-wheel steering(4WS)system through the step input and the double lane change test. The simulation results of 4WIS system show the similar handling performance with those of the conventional 4WS system and the total consumed power to control the system in rear wheels was much reduced.