This paper proposes a novel interval observer design method for discrete-time Takagi-Sugeno fuzzy systems with parametric uncertainty, disturbances, and measurement noise. We present a new structure of interval observer with more design parameters, which can be used to broaden the application scope of interval observer design. For improving the accuracy of interval estimation, an L _∞ norm-based approach is used in the design of interval observer to attenuate the effect of the unknown disturbances, noise, and parametric uncertainty. Furthermore, the design conditions are formulated into a set of linear matrix inequalities, which can be efficiently solved. Numerical simulations are given to illustrate the effectiveness of the proposed method.

This article deals with the problem of fault detection for discrete-time Lipschitz nonlinear systems subject to a class of restricted frequency-domain specifications. We present a novel observer structure with more design parameters, which can be applied to enhance the observer performance. The performances of fault sensitivity and disturbance robustness are characterized using finite-frequency $H_{-}$ and $H_{\infty }$ indices, respectively. Less restrictive design conditions are obtained based on a reformulated Lipschitz property. Moreover, to detect faults timely, a novel dynamic threshold is synthesized based on zonotopic set-membership techniques. Simulation examples are conducted to demonstrate the viability and validity of the presented method.

This article studies the problem of sensor attack detection for a class of cyber-physical systems with bounded perturbations. A novel attack detection method is proposed based on zonotopic reachability analysis. A false data injection attack is detected if there is no intersection between the predicted state set and the measurement state set. These sets are online calculated via zonotopic segments minimization. Two approaches, namely, projection and polytopic conversion, are presented to check the intersection situation. The detection performance is quantified using a stealthy attack set and the corresponding state estimation error set. Further, we consider replay attacks. To detect a replay attack, a watermark signal-based active detection mechanism is introduced. Numerical simulations are conducted to demonstrate the validity of the proposed method.

This note studies unknown input observer design for linear parameter-varying systems in a bounded error context. By presenting a novel unknown input observer structure, the output equation of linear parameter-varying systems is not restricted to be in a linear form. Moreover, by integrating decoupling technique and set-membership approach, a compromise is achieved between the restrictiveness and the conservativeness of estimation. Based on P-radius criteria, sufficient design conditions are derived and expressed in terms of linear matrix inequalities. Finally, numerical simulations of a continuous stirred tank reactor and a vehicle lateral dynamics system are conducted to demonstrate the validity of the presented method.

In this work, we consider the detection of velocity sensor faults for autonomous underwater vehicles in a bounded error context. The nonlinearity of autonomous underwater vehicles is handled via a Takagi-Sugeno fuzzy technique. The fault detection is achieved by solving a zonotopic enclosure problem based on zonotopic reachability analysis. To improve fault detection performance, a novel observer structure and H $_{-}$ performance index are introduced. The performance of the presented approach is analyzed utilizing a hidden fault set. Experimental examples are given to validate the effectiveness of the presented approach.

This article studies the security synthesis of cyber–physical systems subject to stealthy attacks via zonotopic set theory. The set is used to quantify the effect of potential stealthy attacks on systems. Control performance and security level are characterized using $L_{\infty }$ performance index and the radius of the attack-induced state set, respectively. Sufficient design conditions are given to optimize the security while guaranteeing a prescribed level of control performance. Simulation examples are conducted to demonstrate the effectiveness of the proposed method.