Observer-Based Optimal Fuzzy Control for Networked IT-2 Fuzzy Systems Against Hybrid Cyber-Attacks

This article investigates observer-based optimal fuzzy control for networked interval type-2 (IT-2) fuzzy systems against hybrid cyber-attacks, including aperiodic denial-of-service and deception attacks. First, a hybrid cyber-attack model is constructed after denoting a nonlinear system with parameter uncertainties and external disturbances via an IT-2 fuzzy model. Then, the switched fuzzy observer is derived to estimate the unmeasured states of the system. Second, by introducing the newly designed algorithm, a novel optimal adaptive fuzzy event-triggered strategy is proposed. This mechanism effectively reduces the communication burden and enhances flexibility in handling hybrid cyber-attacks. Third, by employing a new piecewise Lyapunov–Krasovskii functional that incorporates membership functions (MFs), a fuzzy controller with imperfect MFs is designed, where both the MFs and their derivatives are considered. Eventually, sufficient conditions are developed to ensure that the networked IT-2 system is mean square exponentially stable with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ H_\infty$</tex-math></inline-formula> performance. Finally, the merits and applicability of the proposed approaches are exemplified by a practical example.