Robust two-degree-freedom control for multi-axle steering vehicle

In order to improve robust stability of multi-axle steering vehicle, the unified dynamic model was built; and the uncertain structure and certain structure of this model were separated by LFTs (Linear Fractional Transformations). Then two-degree-freedom controller design method was proposed for the multi-axle steering vehicle, where the feedforward controller was actually the model matching problem, and the feedback controller was μ analysis and synthesis problem. The simulation results showed that the velocity variations were compensated by feedforward controller independently, and the perturbations introduced by variations of road adhesion, tire cornering stiffness etc were restrained by feedback controller, and the system achieved zero sideslip angle and ideal yaw rate preferably. In conclusion, the control method can assure the good tracing performance and robustness for the vehicle system.