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This article deals with the adaptive prescribed performance tracking for nonlinear time-varying systems. To handle multiple unknown control directions, a novel lemma is established by using a general class of Nussbaum functions. To handle unknown time-varying parameters, the congelation of variables method is employed. Different novel functions are introduced to achieve prescribed performance tracking and finite-time prescribed performance tracking, respectively. Meanwhile, the problem of explosion of complexity is avoided by utilizing the command filter and the compensation mechanism. For reasons of saving network resources and reducing communication burden, a new event-triggered mechanism is proposed, which can circumvent the Zeno behavior. Then, an event-triggered adaptive prescribed performance tracking control scheme is constructed and is extended to event-triggered finite-time adaptive prescribed performance tracking, both of which guarantee that all closed-loop signals are bounded and the trajectory of the tracking error can be limited to the prescribed region. Finally, the availability of the control scheme is demonstrated by two examples. • A new Nussbaum lemma is tailored for nonlinear time-varying systems with multiple unknown control directions. • New performance transformation functions are designed to achieve asymmetric global prescribed performance tracking. • The command filter and a novel error compensation scheme are constructed to handle the explosion of complexity. • The congelation of variables method is adopted to cope with unknown time-varying parameters. • An STETS adaptive prescribed performance tracking controller is constructed, which can avert the Zeno behavior successfully. [ABSTRACT FROM AUTHOR]

This paper is centered on delay-dependent state feedback stabilization for a networked control model with two additive input delays. Firstly delay-dependent stability is investigated. By splitting the whole delay interval into subintervals according to the delays, a Lyapunov functional is constructed. To reduce conservatism we handle the Lyapunov functional in two ways. More specifically, we take the Lyapunov functional as a whole to examine its positive definite, rather than restrict each term of it to positive definite as usual. In addition, when estimating the derivative of the Lyapunov functional, we manage to get a fairly tighter upper bound by introducing different slack variables for the different subintervals. The resulting stability results turn out dependent on the two delays separately, and less conservative than some existing ones. Then, based on the stability results state feedback stabilization is studied. Delay-dependent conditions are formulated for the controller such that the closed-loop system is asymptotically stable. Finally examples are given to show the less conservatism of the stability results and the effectiveness of the proposed stabilization method. [ABSTRACT FROM AUTHOR]

Abstract: This paper is concerned with the design of the novel observer that synchronizes with the generalized Lorenz chaotic systems. A simple reduced-order observer scheme is proposed by including extra terms. The boundedness of the state variables in the original system is not necessary for the observer design. The prior knowledge on the derivative signal of the system output is not required. It is also shown that by adopting Lyapunov method and choosing appropriate design parameters, the synchronization (observation) errors can converge to zero exponentially. Finally, numerical examples are provided to illustrate the validity of the theoretical result. [Copyright &y& Elsevier]

Abstract: In this paper, an adaptive control scheme is proposed for the synchronization of two single-degree-of-freedom oscillators with unknown parameters. We only assume that the master system has the bounded solutions, which is generally satisfied for chaotic systems. Unlike the existing literature, the boundedness of the states of the slave system with control input is not necessarily known in advance. The boundedness of the controlled states is rigorously proved. The unknown parameters not only in the slave system but also in the master system are estimated by designing adaptive laws. By choosing appropriate Lyapunov function and employing Barbalat’s lemma, it is theoretically shown that the synchronization errors can converge to zero asymptotically. Finally, two illustrative examples are provided to demonstrate the effectiveness of the proposed adaptive control design. [Copyright &y& Elsevier]

Abstract: This paper addresses the problem of adaptive stabilization of uncertain unified chaotic systems with nonlinear input in the sector form. A novel representation of nonlinear input function, that is, a linear input with bounded time-varying coefficient, is firstly established. Then, an adaptive control scheme is proposed based on the new nonlinear input model. By using Barbalat’s lemma, the asymptotic stability of the closed-loop system is proved in spite of system uncertainties, external disturbance and input nonlinearity. One of the advantages of the proposed design method is that the prior knowledge on the plant parameter, the bound parameters of the uncertainties and the slope parameters inside the sector nonlinearity is not required. Finally, numerical simulations are performed to verify the analytical results. [Copyright &y& Elsevier]

The main focus of this paper is to explore the finite-time stabilization of mean-field time-varying stochastic systems that are affected by uncertain parameters, multiple disturbances, and delays. In contrast to prior studies, we present a set of sufficient conditions for achieving finite-time stability in the closed-loop model. Notably, these conditions are established based on the analysis of the state transition matrix (STM). Additionally, we address a sufficient condition based on the Lyapunov function, where the STM significantly simplifies the selection process of the Lyapunov function. Finally, we introduce a linear matrix inequality (LMI)-based approach that facilitates the computation of non-fragile controllers. The effectiveness of the developed theoretical results is verified through a stock investment model. [ABSTRACT FROM AUTHOR]

• The observer design problem for nonlinear switched systems with quantization has been investigated. • A more practical and complex situation that is the uncertainties existing in system parameters and observer gains simultaneously has been studied. • New suficient conditions have been obtained. This paper addresses the nonfragile H ∞ observer design problem for uncertain nonlinear switched systems with quantization. The measurement output signals are quantized by a static quantizer before being transmitted. The sector bound approach is applied to obtain the quantization error. To address the problem of observer parameter perturbation, a set of observers with gain variations are constructed. Considering uncertainties existing both in switched systems and observer gains, our purpose is to design a set of robust nonfragile observers such that the observer error systems are globally exponentially stable and satisfy a weighted H ∞ performance index. Based on the average dwell time (ADT) switching approach and some lemmas, sufficient conditions for the desired observers are established in form of linear matrix inequalities (LMIs). Finally, an example is provided to illustrate the applicability of the obtained results. [ABSTRACT FROM AUTHOR]

• An hidden Markov model is used to avoid some imperfect hypotheses when handling the synchronization control issue for MJNNs. • The HMM is with partial known detection probabilities, which can remedy the disadvantage of some previous works. • Activation function dividing method is used to get less conservative result for the synchronization control issue for MJNNs. This paper pays attention to the synchronization control issue for Markov jump neural networks with partial information on system modes (or called Markov states), which leads to the case that the system modes cannot be directly accessed. An hidden Markov model (HMM)-based detector with partially known detection probabilities is employed to detect the system modes. With the help of the HMM and an activation function dividing method, a less conservative controller design technique is established. The designed HMM-based controller can be converted to mode-independent/-dependent one by suitably adjusting some design parameters. Finally, the availability of the established HMM-based controller design technique is verified by an illustrative example. [ABSTRACT FROM AUTHOR]

In modern control theory, it is more applicable for digital computers using a sampled-data controller than a continuous-time controller. Meanwhile, input saturation and disturbance inevitably exist in control systems. Thus, how to propose an applicable sampled-data controller for nonlinear systems considering input saturation together with external disturbances is essential for applications. To deal with this control problem, a novel auxiliary control signal is designed in this paper. Then, by using Lyapunov method, the control design process is simplified compared with the traditional backstepping technique, and only one Lyapunov function is needed. In addition, the state and disturbance observers are proposed with the new auxiliary control signal to track the unavailable states and external disturbances. Finally, we propose a novel controller reflecting the sampled-data output-feedback for the nonlinear systems to ensure the system stability. The effectiveness of proposed control method in this paper is confirmed through two sets of numerical simulation results. [ABSTRACT FROM AUTHOR]

Abstract This paper is concerned with the problem of non-fragile delay feedback control for neutral stochastic Markovian jump systems (NSMJSs) with time-varying delays. The main aim is to design non-fragile and mode-dependent delay feedback controller (DFC) both in the drift part and in the diffusion part to realize closed-loop NSMJS is stochastically stable. By constructing mode-dependent and delay-dependent comprehensive Lyapunov-Krasovskii functional, the stabilization conditions are provided in terms of linear matrix inequalities (LMIs). Simulation examples including a lossless transmission line model (LTLM) are utilized to verify the validity and usefulness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of reachable set estimation for a class of uncertain singular systems with time-varying delays from a new point of view. Our consideration is centered on the design of a proportional-derivative state feedback controller (PDSFC) such that the considered singular system is robustly normalizable and all the states of the closed-loop system can be contained by a bounded set under zero initial conditions. First, a nominal singular time-delay system is considered and sufficient conditions are obtained in terms of matrix inequalities for the existence of a PDSFC and an ellipsoid. In this case, the considered system is guaranteed to be normalizable and the reachable set of the closed-loop systems is contained by the ellipsoid. Then, the result is extended to the case of singular time-delay systems with polytopic uncertainties and relaxed conditions are derived by introducing some weighting matrix variables. Furthermore, based on the obtained results, the reachable set of the considered closed-loop singular system can be contained in a prescribed ellipsoid. Finally, the effectiveness of our results are demonstrated by two numerical examples. [ABSTRACT FROM AUTHOR]

• The mean-square exponentially admissibility and stabilization for NSMJSs with mixed interval time-varying delays are fully considered by state decomposition approach. • Proposed criteria are established with fewer decision variables and lower computing costs. • The derived results are less conservative than the existing ones. This paper focuses on the mean-square exponentially (ME) admissibility and stabilization for neutral singular Markovian jump systems (NSMJSs) with mixed interval time-varying delays. With the aid of state decomposition approach, a state decomposition Lyapunov-Krasovskii functional (LKF) is founded and some mode-dependent conditions are given to guarantee the unforced NSMJSs to be ME admissible. On this basis, a mode-dependent state feedback controller is presented. By solving the decomposition components of state feedback control parameters, the designed state feedback controller is obtained. It should be pointed out that our results complement and improve the results of the existing literatures. By two number-based examples, the advantage and availability of our methods are presented. [ABSTRACT FROM AUTHOR]

• The dissipative filter design problem for discrete.time Markovian jump systems subject to additive time.varying delays is investigated by using event.triggered scheme. • Different from the classical methods, a novel mode.dependent Lyapunov functional which contains multiple matrices related to jumping modes is constructed. • In order to obtain a less conservative stability criterion, the Wirtinger.based inequality and a refined matrix inequality are employed. • The scheme developed in this paper can be extended to deal with the controller/filter design problem for other dynamic systems. This paper focus on the event-triggered filter design problem for delayed discrete-time Markovian jump systems. Firstly, a new mode-dependent Lyapunov-Krasovskii functional is introduced, where more than one Lyapunov matrices are dependent on jumping modes. Secondly, sufficient conditions are established by employing the Lyapunov stability theory together with Wirtinger-based inequality, under which the filtering error system is stochastically stable with strict dissipative. Thirdly, the co-design scheme of the filter parameters and event-triggered matrices is proposed. Finally, two numerical examples are given to show the usefulness of the proposed scheme. [ABSTRACT FROM AUTHOR]