Abstract
This paper addresses the problem of stability augmentation for coupled lateral and longitudinal vehicle dynamics, with emphasis on using control and stability criteria within a general non-linear framework. An idealised vehicle system is considered, equivalent to a vehicle with fully independent 4WS and traction/braking control. Particular attention is devoted to the problem of achieving stable control in the presence of large and uncertain variations in road friction. Two control schemes are investigated, and it is found that one based on a simple Lyapunov function is very effective.