Abstract: For further research on the dynamic behavior of three-axle vehicle with all-wheel steering system, an all-wheel steering vehicle dynamic model is built considering the nonliner characteristics and load changes of wheels. To improve the handling stability of three-axle vehicle with all-wheel steering system, an all-wheel steering controller is designed based on the siding mode variable structure control theory, which can follow a reference model that contains an ideal yaw rate of the double-front-axle steering vehicle and the zero side-slip model. The double-front-axle steering vehicle, the all-wheel steering vehicle with zero side-slip angle proportional controller and the all-wheel steering vehicle with sliding mode controller are compared under different conditions. The result shows that the siding mode controller can ensure the smaller slide-slip angle and the ideal yaw rate, which can resist the interference from lateral wind and road conditions.

Key words: control science and technology, three-axle vehicle, all-wheel steering, ideal model, sliding mode controller