Synchronization Control Problem Research Articles

Nonfragile synchronization control of T-S fuzzy Markovian jump complex dynamical networks

This paper investigates the nonfragile dissipativity synchronization control problem of discrete-time Takagi-Sugeno (T-S) fuzzy Markovian jump complex dynamical networks. Considering the randomly occurring uncertainty, the nonfragile synchronization controller is proposed. According to the strict dissipative performance, a sufficient condition is developed to ensure that the complex network is stochastically stable by using the fuzzy-basis-dependent and mode-dependent Lyapunov function. Then, new design conditions about the nonfragile controller are obtained in the form of linear matrix inequalities. Finally, the validity of the established theoretical results is illustrated by a numerical example.

Distributed dynamic event-based finite-time dissipative synchronization control for semi-Markov switched fuzzy cyber-physical systems against random packet losses

This paper is concerned with the finite-time dissipative synchronization control problem of semi-Markov switched cyber-physical systems in the presence of packet losses, which is constructed by the Takagi–Sugeno fuzzy model. To save the network communication burden, a distributed dynamic event-triggered mechanism is developed to restrain the information update. Besides, random packet dropouts following the Bernoulli distribution are assumed to occur in sensor to controller channels, where the triggered control input is analyzed via an equivalent method containing a new stochastic variable. By establishing the mode-dependent Lyapunov–Krasovskii functional with augmented terms, the finite-time boundness of the error system limited to strict dissipativity is studied. As a result of the help of an extended reciprocally convex matrix inequality technique, less conservative criteria in terms of linear matrix inequalities are deduced to calculate the desired control gains. Finally, two examples in regard to practical systems are provided to display the effectiveness of the proposed theory.

Distributed periodic event-triggered synchronization for discrete-time complex dynamical networks with time-varying delay

In this paper, we study the synchronization control problem for a class of discrete-time complex dynamical networks (CDNs) under an event-triggered mechanism (ETM). First, a discrete-time distributed periodic ETM is developed based on communication measurement. Under this mechanism, the signal is sampled in a periodic manner, but whether the control signal is updated or not depends on the pre-designed triggering condition. The sampling signal is designed as the communication measurement calculated by both state feedback and inner communication among nodes. Compared with the existing discrete-time ETMs, this method considers the topology connection among network nodes and avoids the continuous measurement of signals. Therefore, this mechanism effectively saves communication resources and reduces the waste of computing resources. Second, in order to analyze the serrated constraint caused by the periodic sampling error, a piecewise Lyapunov function is constructed. Third, under the distributed periodic ETM, sufficient conditions are derived for bounded synchronization of discrete-time CDNs with time-varying delay. Finally, a simulation example verifies the effectiveness and accuracy of the conclusion.

Resilient Synchronization of Networked Lagrangian Systems Over Event-Based Communication With Asynchronous DoS Attacks

A wide range of actual systems can be modeled as Euler- Lagrange dynamics, its inherently complex nonlinearities present additional difficulties in the design of control algorithms. In this paper, the distributed resilient synchronization control problem of networked Euler- Lagrange (E-L) systems under event-based communication with distributed denial-of-service (DoS) attacks is considered. A novel distributed dynamic event-triggered scheme is proposed to schedule the communication source under asynchronous DoS attacks on different channels. Then, a self-triggered scheme is designed to reduce the updating number of the control signals. Under the proposed adaptive control scheme, the asymptotic synchronization of the closed-loop system is guaranteed under DoS attacks. Neither the control strategy nor the dual-terminal event-triggered scheme needs the eigenvalue information of the Laplace matrix. Also, no Zeno behavior occurs under the proposed event-based control and communication framework. Finally, case studies are provided to show the effectiveness of the proposed method.

Disturbance observer-based adaptive sliding mode synchronization control for uncertain chaotic systems

<abstract><p>The synchronization control problem of a class of chaotic systems with unknown uncertainties and outside perturbation is addressed in this article by employing an innovative adaptive sliding mode controller (SM, SMC) constructed using a disturbance observer (DO). For the synchronous error system, the external disturbances estimated by the disturbance observer cannot be measured directly. If the appropriate gain matrix is chosen, the DO can approximate the unknown external disturbances well. Then a continuous adaptive SM controller based on the DO's output is designed by using adaptive techniques and the system dimensional expansion method. The Duffing-Holmes chaotic system is finally selected to numerically test the efficiency of the suggested strategy.</p></abstract>

Intermittent Control for Synchronization of Discrete-Delayed Complex Cyber-Physical Networks under Mixed Attacks

This paper is concerned with the synchronization control problem for discrete-delayed complex cyber-physical networks under mixed attacks. To handle input delays and mixed attacks, the intermittent control mechanism is employed, which is distinctly different from the traditional control method. By utilizing the Lyapunov stability theorem, a novel synchronization control method is developed for the synchronization control of complex cyber-physical networks with mixed attacks. Then, sufficient conditions are derived to guarantee that the synchronization error dynamics are ultimately bounded. Moreover, the conditions for a special case where the absence of input delays. Subsequently, certain optimization problems are formulated with the aim to minimize the synchronization error. Finally, two numerical examples are given to verify the effectiveness and superiority of the proposed synchronization control strategy.

Jamming-Resilient Synchronization of Networked Lagrangian Systems With Quantized Sampling Data

A wide range of cyber–physical systems can be modeled as Euler–Lagrange dynamics, whose inherent nonlinearities bring additional difficulties in the design and analysis of controllers for such systems. The objective of this article is to solve the jamming-resilient synchronization control problem of networked Lagrangian systems subject to unknown external disturbances, with the quantized sampling data. Under a jamming attack, a normal communication channel will be blocked with unknown frequencies and intervals. To achieve jamming attack resilience, a robust adaptive controller is proposed. Then a novel auxiliary system is designed for each subsystem over a directed network. By using the quantized sampling data from each subsystem and its neighbors, the jamming attack can be handled by an embedded single-integral subsystem. Sufficient conditions that are independent of the attack parameters are derived to guarantee the global stability of the closed-loop system. Compared with existing jamming-resilient methods, the proposed approach is concise and resilient to any jamming attacks with bounded frequencies and durations.

Adaptive synchronization control of multimanipulator teleoperation system under constrained discrete‐time network communication

AbstractThis paper addresses the synchronization control problem of uncertain single‐master multislave (SMMS) teleoperation system in which every subsystem is connected with each other via a directed constrained communication network. The data exchanges in the channel are discrete in time, intermittent in presence of irregular delays and packet loss, which make the synchronization problem more challenging and still not be well explored. We propose a new adaptive control scheme based on the virtual model and the original dynamic compensator entailing synchronization of all the subsystems under the limited communication. The most recently transmitted information is used to construct the control signal during sampling interval or the period of data loss. The validity of the control approach designed is verified by some simulation results.

Discrete spatiotemporal network synchronization based on adaptive control

This paper first introduces the basic concept of network synchronization and several common synchronization types. Secondly, aiming at the synchronization control problem of a class of discrete spatiotemporal networks, a standard synchronization control strategy and a synchronization controller are proposed based on Lyapunov stability theory. In order to further verify the effectiveness of the synchronization theory, the spatiotemporal network model is selected, the coupling matrix and the identification rate of unknown parameters are designed for numerical simulation. Finally, the simulation results show the feasibility of the theory.

Approximation-Free Robust Synchronization Control for Dual-Linear-Motors-Driven Systems With Uncertainties and Disturbances

This article addresses the synchronization control problem for dual-linear-motors-driven systems with model uncertainties and disturbances. An approximation-free robust synchronization control scheme based on cross-coupled control (CCC) frame is proposed to achieve high-precision tracking and synchronization performance, along with excellent uncertainties and disturbances rejection ability. More specifically, the CCC frame is designed to handle the asynchronous motion of two parallel motors. The main advantage is that the proposed method does not require the explicit system model, and any approximations utilized to handle the model uncertainties, such as estimation, identification, and online learning, are not required. Therefore, the computational burden and complexity of the controller are significantly reduced. Considering the importance of the transient and steady-state response, the concept and technology of prescribed performance are adopted to guarantee the control effect and state constraints. In addition, none of the high-order derivatives of desired trajectory, difficult to obtain directly in many applications, are used in the proposed controller. Furthermore, the stability and convergence performance of the closed-loop system are rigorously demonstrated. Finally, comparative experiments show the effectiveness of this study via a dual-driven H-type gantry.

Synchronization Control for Coupled Delayed Neural Networks With Time-Varying Coupling via Markov Pinning Strategy

In this article, a novel Markov pinning strategy, where each mode corresponds to a specific pinning strategy and the switches from one specific pinning strategy to another are governed by the transition probability matrix, is proposed for synchronization control problem of coupled delayed neural networks. With consideration that topological structures of networks are usually time-dependent, a general polytopic time-varying coupling model is studied. In coupled delayed neural networks, each node frequently exchanges information with its neighboring nodes so as to realize synchronization. Since communization network is with limited transmission resource, network congestion may occur, and thus information of neighboring nodes may not be available. Furthermore, as the amount of information that needs to be transmitted will change with the number of pinned nodes, packet dropout rate is considered to be random switching. By Lyapunov function method, a sufficient condition is obtained to globally synchronize the coupled delayed neural networks, and then the Markov pinning controller is designed. Finally, an illustrative example, where all nodes synchronize quickly under the control of Markov pinning controller, is used to demonstrate the advantages and potential of the new design strategy.

A Pulse Delay Control Method by External Trigger to Underwater Illumination

Aiming at the problem of high precision pulse synchronization control in digital signal processing, we proposed an external trigger synchronization control method by double-layer hierarchical delay. The method consists of hardware circuit and control algorithm. The hardware circuit employs the main control unit and the digital delay unit, in which the main control unit makes the coordination between the digital delay unit and the peripheral circuit, and the two-layer digital delay unit performs multiple fixed period delay operation according to the instruction of the main control unit. The control algorithm adopts the two-layer hierarchical control mode, decomposes the total delay time according to the two-layer delay precision, and performs the combined delay in the two-layer digital delay unit successively. The delay result achieves a fixed delay of less than 40 ns, a delay step of 0.25 ns and a delay range of less than 1000 ns. The method adopts the combination of hardware and software to realize the external trigger double-layer hierarchical delay synchronization control, which has the characteristics of high delay step and pulse width adjustment accuracy and small cumulative delay error. It is suitable for the application scenarios of lidar echo signal and ultra-wide spectrum power source synthesis.

Finite-Time Prescribed Performance Control for Space Circumnavigation Mission With Input Constraints and Measurement Uncertainties

This article presents a 6-DOF attitude-orbit synchronous control problem for the space circumnavigation (SCN) mission with parameter uncertainties, time-varying uncertainties, and input constraints. In particular, from the perspective of engineering application, time-varying measurement uncertainties are taken into account of the 6-DOF attitude–orbit coupling kinematics and dynamics, and the analytical solution of the desired attitude is derived based on the measured relative orbit information with measurement uncertainties. To drive the active spacecraft approach to the faulty target safely, a time-varying exponential prescribed convergence boundary is introduced into the sliding surface. A finite-time disturbance observer is involved in equivalent tracking errors for compensating the mismatched uncertainties. In addition, an auxiliary system is designed to overcome the instability danger caused by input constraints. The stability of the controlled system is discussed in the nonautonomous finite-time stable framework, which is proved via Lyapunov analysis that the attitude-orbit tracking errors converge to the equilibrium within finite time. The simulation experiment with mismatched uncertainties and prescribed constraints shows the superiority of the designed control scheme.

Adaptive synchronization control for stochastic complex networks with derivative coupling

In this paper, the problem of the adaptive synchronization control is studied for a class of stochastic complex networks with unknown nonlinear coupling strength and derivative coupling. First, in order to deal with the unknown nonlinear coupling strength, Takagi–Sugeno (T–S) fuzzy method is used to transform the network model into a T–S fuzzy complex network model. Then,a fuzzy adaptive controller and the corresponding adaptive parameter update rate are designed. Subsequently, a new Lyapunov function is constructed, which is related to the derivative coupling. By employing the stochastic analysis technique and Lyapunov stability theory, a sufficient condition is given for exponential stabilization in mean square of the synchronization error system. Finally, the effectiveness of the obtained theoretical results is verified through a simulation.

Constrained adaptive fuzzy super-twisting control for space circumnavigation mission with input constraints and rough dynamics information

The 6-DOF attitude-orbit fast synchronous control problem in the space circumnavigation mission is investigated in this paper with dynamics coupling, uncertainties and disturbances, input constraints, and rough dynamical information feedbacks. The orbital-information-based desired angular acceleration information is dynamically compensated via a set of hierarchical fuzzy systems to avoid the derivation operation of orbital states amplifying measurement noise. Since the adaptive laws for updating fuzzy weights are developed based on hyperbolic tangent function, estimation results are updated slowly, even if the initial tracking errors are large. A novel nonsingular practical terminal sliding-mode (PTSM) reduced-order system is proposed for drive tracking errors fast converge with high precision. Benefiting from the absence of information coupling in the derivative of the PTSM function, an observation-based super-twisting algorithm (STA) is employed to establish the PTSM manifold with weakened chattering. Adaptive laws estimate the maximum uncertainty, and an auxiliary system compensates for the input constraints. Simulation results verify the effectiveness of the proposed control scheme.

Fault-Tolerant Cooperative Control for Multiple Vehicle Systems Based on Topology Reconfiguration.

In this article, the fault-tolerant synchronization and time-varying tracking control problem is investigated for nonlinear multivehicle systems (MVSs) in the presence of partial loss-of-control-effectiveness (LoCE) faults. Based on the graph theory, a two-level fault-tolerant cooperative control framework is proposed, namely, the low-level distributed nominal control scheme and the high-level topology reconfiguration protocols. The low-level scheme is developed to guarantee system performances in the fault-free scenario. With the low-level scheme, the high-level topology reconfiguration protocols, each of which corresponds to one partial LoCE fault scenario, are then proposed to mitigate the fault impact by adjusting the underlying topology. Accordingly, without modifying the structure or the design parameter of the low-level control scheme, the proposed framework can guarantee the synchronization and tracking errors of the MVS asymptotically convergent to zero in both fault-free and fault scenarios. Finally, the effectiveness of the proposed control method is verified via a simulation study of three degree-of-freedom helicopters.

Finite-Time Synchronization Control of Networked Chaotic Complex-Valued Systems With Adaptive Coupling

In the present paper, the finite-time synchronization control problem is addressed for the networked complex-valued dynamical systems with directed and undirected topologies. By combining the two-phase method with delayed impulsive control and designing adaptive coupling weights, several finite-time synchronization results and the corresponding settling times are obtained by using the complex-valued states directly. In particular, the delayed impulsive control is introduced in the first phase to guarantee that the controlled system can globally exponentially converge to the inner of the unit ball, while the finite-time control term is used only in the second phase to ensure the finite-time stability. Finally, two numerical examples are used to show the validity of our control strategy.

Observer-based synchronisation control for discrete-time delayed switched complex networks with coding–decoding approach

ABSTRACT In this paper, we investigate the synchronisation control problem for a class of discrete-time switched complex networks with time-varying delays via a coding–decoding-based approach. An observer-based control scheme is proposed for each node by utilising the outputs of complex networks. The data are transmitted in a digital manner and only the sequence of finite coded signals is sent from the observer to the controller. We design a proper coding–decoding procedure for each node to ensure that the closed-loop networks achieve the expected synchronisation performance. By applying the average dwell-time switching strategy and a uniform quantisation approach, some criteria are firstly presented to ensure the detectability of the complex networks. Then sufficient conditions are provided for the existence of desired observer-based controller, guaranteeing the synchronisation of complex networks. Finally, a numerical example is given to illustrate the effectiveness of the obtained theoretical results.

Adaptive event‐triggered synchronization control for bilateral teleoperation system subjected to fixed‐time constraint

SummaryThe time‐constrained positional synchronization control problem for a class of bilateral teleoperation systems is investigated and a novel fixed‐time event‐triggered control scheme is developed. Different from existing methods, the controller is triggered in a nonperiodic manner, which reduces considerably the triggering frequency of control devices. This not only saves communication resource, but also extends the lifespan of system devices because of the reduction of switching times. The control settling time is further considered by introducing a fixed‐time stability theorem. Theoretical analysis as well as a simulation example verifies that the proposed control method can reduce remarkably the amount of control signals transmitted between the master and slave while ensuring that the system output tracking error converges to a small neighborhood close to zero within a fixed‐time frame.

Static output feedback secure synchronization control for Markov jump neural networks under hybrid cyber-attacks

This paper investigates the secure synchronization control problem for Markov jump neural networks subjected to cyber-attacks where the synchronization controller is based on mode-independent static output feedback strategy. The communication networks are supposed to be subject to mixed forms of cyber-attacks: deception attack and denial of service attack. The fundamental purpose concentrates that how to achieve stochastic stability of closed-loop system by applying the static output feedback strategy regardless of whether hybrid cyber-attacks occur. Furthermore, with the help of Lyapunov stability theory and linear matrix inequality technology, sufficient conditions to guarantee that the closed-loop system satisfies the specified H∞/passive performance are established. Then, the specific expression of static output feedback controller is indicated by an effective decoupling method. Eventually, a numerical example verifies the effectiveness of the proposed approach.