Optimal Control of Four Wheel Steering Vehicle

This paper derives a method of controlling four wheel steering using optimal control theory. The purpose of control is to minimize the sideslip angle at the center of gravity. The control method feeds forward the steering wheel angle and feeds back the yaw velocity and the sideslip angle to the front and rear wheel angles. Theoretical studies show that the sideslip angle is reduced to zero even in the transient state, and that the understeer characteristic and frequency response can be changed regardless of the vehicle static margin. This Paper also examines various characteristics of the influence of the side force nonlinearities of tires and crosswinds.