Observer-Based Fuzzy Control for Four-Wheel Independently Driven Electric Vehicles with Active Steering Systems

This paper presents an observer-based control strategy to improve the maneuverability and stability performance of four-wheel independently driven electric vehicles with active front-wheel steering systems. Since the system states are difficult to be measured directly, a novel observer is designed to estimate the vehicle yaw rate and lateral velocity simultaneously. Takagi-Sugeno fuzzy model is used to handle the time-varying parameters of the vehicle model. Based on Lyapunov function theory, stability conditions of the closed-loop system are derived. The fuzzy \begin{document}$$H_{\infty }$$\end{document} controller is designed to make the resulting T-S fuzzy system asymptotically stable and satisfy