Application of variable-structure output feedback control to active front steering for understeer and oversteer conditions

This paper describes an approach to the design of Active Front Steering (AFS) based on Variable-Structure Output Feedback Control (VSOFC) with integral action to enhance vehicle stability during understeer and oversteer conditions. We determine the understeer and oversteer behaviour of the vehicle and we change the AFS control strategy based on the understeer and oversteer behaviour of the vehicle so that the road wheel steering angle is in the ideal position to provide the intended steering angle. The control law ensures not only that the vehicle trajectory follows a desired reference trajectory but also that its convergence rate can be specified. Finally we present simulation results to demonstrate the potential benefits of the control strategy under different driving scenarios.