International Journal of Robust and Nonlinear Control最新文献

This paper studies the issue of non-fragile dissipative load frequency control (LFC) for multi-area power systems. Firstly, the impacts of high penetration wind power (HPW) and multiple time-varying delays (MTD) are considered to establish the LFC model. Then, reconfiguration technology is employed, improving the computational efficiency of stability analysis. Especially, this technology can dynamically partition the model according to time delays. Subsequently, a Lyapunov–Krasovskii function (LKF) is constructed, which includes delay terms, effectively reflecting the impact of multiple delays on stability analysis. Next, the novel integral inequality is used to solve the integral terms in the LKF, thereby significantly reducing the conservatism of the stability criterion. In addition, the non-fragile dissipative controller (NFDC) is designed, considering controller gain disturbances. It solves two types of uncertainty problems and thus improves the robustness of the power system. Finally, the superiority of the stability criterion and the effectiveness of the control method are verified through simulation experiments.

This study investigates the finite-time inverse optimal control problem for low-order stochastic nonlinear systems with time-varying orders. By designing a state feedback controller to ensure the finite-time stabilization of the system, and subsequently applying the finite-time inverse optimal control principle, we redesign an optimal controller. This paper combines inverse optimal control with finite-time stability and introduces it for the first time to low-order stochastic nonlinear systems. It ensures that the designed controller is not only optimal in terms of meaningful cost functions but also capable of globally stabilizing the closed-loop system within a finite time. Two examples are given to validate the feasibility of the proposed scheme.

This paper addresses the non-fragile sampled-data control problem for path following of autonomous electric vehicles (AEVs) with semi-Markov jump actuator failures. Firstly, due to the uncertainty of tire dynamics, linear fractional transformation formulations are used to describe the lateral dynamics of AEVs. Secondly, to accurately depict the stochastic actuator failures, the proposed actuator failures model incorporates a semi-Markov jump process with partially unknown transition rates. Moreover, a non-fragile control strategy is adopted to enhance the robustness of the controller. Thirdly, a two-sided looped Lyapunov functional is constructed to alleviate the positivity constraints over the whole sampling interval. Furthermore, based on the two-sided looped Lyapunov functional and free matrix-based integral inequality, some sufficient conditions are derived in the form of linear matrix inequalities to ensure the AEVs are stochastically stable with $��{�H�}_{�\infty �}�$ performance. Ultimately, the correlative simulation is carried out to validate the effectiveness of the proposed method.

This paper focuses on the challenge of integrated active fault-tolerant control (IAFTC) for linear discrete-time systems utilizing compatible linear matrix inequality (LMI) techniques. The presence of input nonlinearity, additive faults, external disturbances, and uncertainty in the system matrix makes this problem more applicable to real-world systems while expanding the complexity and functional range. In such a situation, the designer must take an integrated approach instead of synthesizing fault estimation (FE) and fault-tolerant control (FTC) as separate modules; yet, the LMI-based design conditions can be overly conservative. As a result, the reduction of the bi-directional interaction effect between FE and FTC units does not lead to satisfactory improvements in the overall behavior of the control system. To provide an integrated design approach, we propose a dynamic output feedback controller that plays the role of the FTC unit. This scheme incorporates two effective decision parameters and a descriptor observer (As FE), contributing to the IAFTC block's functionality. The design criteria are formulated using tractable LMI constraints in a convex optimization problem, and the $��{�ℒ�}_{�2�}�$-stability criterion is proved for the overall closed-loop system. The superiority and effectiveness of the proposed IAFTC are demonstrated through three comparative simulation examples.

This article addresses the issue of infinite-gain problems that exist in previous works concerning stochastic nonlinear systems, and provides more comprehensive fixed-time stability results with an arbitrarily prescribed upper bound of the settling time (UBST). First, we propose a distinctive and uniformly bounded time-varying gain function that can avoid the infinite-gain problem. Building upon this, we present generalized fixed-time Lyapunov theorems, along with several useful corollaries that incorporate prescribed UBST and offer additional flexibility for the Lyapunov differential operator constraint. These stability results generalize the concepts of finite/fixed-time stability discussed in previous works, while providing a simpler method to prescribe the settling time. Based on the proposed stability theorem, we design a state-feedback controller for stochastic nonlinear systems, which ensures the closed-loop system exhibits fixed-time stability in probability with prescribed UBST. The resulting controller relies on time-varying gains, uniformly bounded over the infinite horizon, thereby yielding an attractive implementation opportunity which is opposed to the design with time-varying gains, escaping to infinity as time goes to the prescribed-time instant. Finally, we provide simulation results to illustrate the effectiveness of the proposed stability and controller designs.

This article addresses the problem of uniformly ultimately bounded (UUB) stability in networked control systems (NCSs) under packet loss and user datagram protocol (UDP) attacks. Since the system is also subject to cyber-attacks when packet loss occurs, we consider the case where packet loss and UDP attacks are asynchronous. First, two sets of Bernoulli models are used to simulate the asynchronous scenarios of packet loss and UDP attacks, and they are incorporated into the controller design to enhance the system's resilience to communication constraints. Second, an algorithm is introduced to extract the moment and interval of packet loss to more accurately calculate the probability of packet loss, thereby reducing the impact of packet loss on the system. Then, a dual-threshold dynamic-memory-event-triggered scheme (DMETS) is proposed to reduce the number of data transmissions to improve network resource utilization while mitigating the impact of packet loss and UDP attacks. In addition, a state feedback controller is designed to ensure UUB stability by utilizing Lyapunov stability theory and linear matrix inequality (LMI) techniques. Finally, the effectiveness and advantages of the proposed controller are verified by simulation of the flight control system.

In this paper, the stability and positive stabilization issues are addressed for discrete-time impulsive switched positive linear systems (DISPLSs) with a novel extended-sequence-pair-dependent (ESPD) hybrid signal. The combination of some common switching and impulsive signals can be seen as special cases of ESPD hybrid signal, such as the arbitrary (dwell time) switching signal and non-periodic (periodic) impulsive signals. Firstly, several necessary and sufficient stability conditions are given for DISPLSs with ESPD hybrid signal. Secondly, based on the non-conservative stability criteria, several necessary and sufficient positive stabilization conditions are presented. Thirdly, the results are extended to the time-delayed cases. Non-conservative stability and stabilization conditions for DISPLSs with multiple time delays are presented. All the results are given in terms of linear programming (LP). Finally, the advantages of the results over the literature are illustrated within four examples.

This study investigates the challenge of repetitive control in a type of linear uncertain system with exogenous disturbances. The uncertain systems with state and state derivative uncertainties. To preserve the uncertain properties of these systems, this class is not directly transformed into a general linear uncertain system. Therefore, it is challenging and complicated to study the control issues of these systems. In this study, a novel approach that combines the system and differential states into a new state is presented; this approach transforms an uncertain system into a linear singular system and is effective for handling uncertainty. The repetitive control problem of the linear singular system with disturbances is addressed from two perspectives. First, the traditional modified repetitive control system is enhanced by introducing an error compensator to improve system tracking performance. Second, to enhance disturbance rejection, a novel modified equivalent-input-disturbance (EID) approach is introduced for the first time. Unlike the traditional EID method, the modified method directly compensates for the disturbance estimation error to enhance the accuracy of disturbance estimation and achieve optimal disturbance-rejection performance in the system. The required and sufficient requirements for the stability of a closed-loop system are provided. And the controller design algorithm is presented based on these conditions. Finally, the presented method is compared with other control methods, demonstrating its effectiveness and superiority.

Based on the sum-of-squares convex optimization method, this paper considers the stability analysis of the isolated equilibrium point for nonlinear parameter-varying systems with state-and-parameter-dependence. As a special kind of nonlinear parameter-varying systems, the criteria of uniform asymptotic stability, exponential stability, and instability for polynomial parameter-varying systems are established by using Lyapunov function and bound functions with state-and-parameter-dependence. The above criteria reduce the conservatism of the existing results and are also applicable to linear parameter-varying systems and state-dependent linear-like systems. For general smooth nonlinear parameter-varying systems, the corresponding polynomial parameter-varying systems can be obtained by Taylor expansion. With reference to the idea of linearization, the polynomial parameter-varying systems can be regarded as a linearization-like model of the plant. It is proven that the stability/instability criteria of the former are also sufficient conditions for local stability/instability of the original system. Finally, three examples are given to illustrate the feasibility of the proposed method.