INVESTIGATION INTO THE STABILITY OF 4 WHEEL STEERING VEHICLES

Automotive manufacturers have recently been developing four wheel steering systems as part of an effort to enhance the dynamic response characteristics of passenger vehicles. The systems being developed by the various manufacturers differ in the control methods used to steer the rear wheels. This paper investigates the stability properties of four different steering control methods in pure cornering manoeuvres at moderate and high speeds, as well as stability properties in combined cornering and braking manoeuvres. A three degree of freedom, non-linear, time domain vehicle model was used to simulate the dynamic behavior of a vehicle using each steering control method.