Cornering stability control for vehicles with active front steering system using T-S fuzzy based sliding mode control strategy

•The vehicle nonlinear characteristics are considered by using the T-S fuzzy approach.•A new sliding mode control strategy is proposed based on the T-S fuzzy approach.•The effective region is considered for the bounded sector zone of the AFS system.•A model parameter observer is designed to obtain the real-time cornering stiffness. Active front steering (AFS) has drawn considerable attention due to its superiority in improving the vehicle safety. This paper proposes a new Takagi-Sugeno (T-S) fuzzy based sliding mode control (SMC) strategy for the AFS system to improve the cornering stability of vehicles. Different from the conventional SMC strategy, the control law of the proposed control strategy is designed based on the T-S fuzzy approach which deals with the nonlinearity of the tire in a simplified but effective way. In the design of the control strategy, the bounded sector zone in the T-S fuzzy approach is determined based on the working region of the AFS system, and a model parameter observer is constructed to obtain the real-time cornering stiffness of the vehicle. To evaluate the cornering performance, simulations are conducted via open-loop and closed-loop tests. Simulation results show that the proposed T-S fuzzy based SMC strategy, which considers the nonlinearity of the tire and multi-objective control, is able to improve the cornering stability of the vehicle as compared with the conventional SMC strategy.