Effects of the lateral compliance of the suspension on the vehicle-handling responses

In the current work the yawing and side-slip motion of a two-mass vehicle is studied. The vehicle is divided into an upper rigid mass and a lower rigid mass pivoted on one another on a vertical axis through the centre of mass. The vehicle body constitutes the upper rigid body, and the suspension axles represent the lower rigid body. A yawing stiffness and damping package is acting between the two rigid bodies. The equations of motion of the two-body yawing vehicle are developed, and the handling behaviour of the vehicle is compared with that of a basic two-degree-of-freedom vehicle-handling model. The steady-state yaw responses of the two systems are equal but the side-slip angles are different. The results show considerable differences in the transient response properties of the two systems. With regard to the stability of motion, at situations where the two-degree-of-freedom model is stable, the three-degree-of-freedom yaw stiff model is also stable.