Sampled-data synchronisation of coupled harmonic oscillators with communication and input delays subject to controller failure

This paper considers the sampled-data synchronisation problems of coupled harmonic oscillators with communication and input delays subject to controller failure. A synchronisation protocol is proposed for such oscillator systems over directed network topology, and then some general algebraic criteria on exponential convergence for the proposed protocol are established. The main features of the present investigation include: (1) both the communication and input delays are simultaneously addressed, and the directed network topology is firstly considered and (2) the effects of time delays on synchronisation performance are theoretically and numerically investigated. It is shown that in the absence of communication delays, coupled harmonic oscillators can achieve synchronisation oscillatory motion. Whereas if communication delays are nonzero at infinite multiple sampled-data instants, its synchronisation (or consensus) state is zero. This conclusion can be used as an effective control strategy to stabilise coupled harmonic oscillators in practical applications. Furthermore, it is interesting to find that increasing either communication or input delays will enhance the synchronisation performance of coupled harmonic oscillators. Subsequently, numerical examples illustrate and visualise theoretical results.     

Synchronization of coupled harmonic oscillators with local instantaneous interaction

In this brief we propose a distributed algorithm for synchronization of coupled harmonic oscillators with local instantaneous interaction. We provide convergence analysis for such algorithm without and with a leader over fixed and switching undirected network topologies, respectively. We also establish the conditions by which the coupled harmonic oscillators achieve synchronized oscillatory motions under instantaneous network connectivity. It is shown that the coupled harmonic oscillators can be synchronized even each oscillator instantaneously exchanges the velocity information with its neighbors only at discrete moments. Subsequently, numerical examples illustrate and visualize the effectiveness and feasibility of the theoretical results.     

Pinning Cluster Synchronization of Coupled Nonidentical Harmonic Oscillators Under Directed Topology

This paper addresses cluster synchronization of coupled harmonic oscillators over directed fixed and switching topologies, where uncoupled harmonic oscillators in the same cluster have the identical node dynamics, while any pair of nodes in different clusters are essentially distinguishing according to their local dynamics. A pinning control protocol is proposed for such coupled harmonic oscillators system, and then some graphic topology conditions easy to verify are established for cluster synchronization. The main contributions of the present investigation include: (i) cluster synchronization problem of coupled nonidentical harmonic oscillators is addressed over directed topology; (ii) desynchronizing motion of harmonic oscillators from different clusters doesn't depend on negative coupling weights but leader of every cluster; (iii) this paper deals with what kind of harmonic oscillators ought to be pinned in order to reach cluster synchronization. Finally, numerical examples and simulations demonstrate the obtained theoretical results.     

Robust semiglobal swarm tracking of coupled harmonic oscillators with input saturation and external disturbance

The robust semiglobal swarm tracking problem of N coupled harmonic oscillators and 1 actual leader with input saturation and external disturbance on a directed communication topology is considered, in which the N coupled harmonic oscillators are referred to followers. First, the low‐and‐high gain feedback technique is introduced to construct a relative state‐dependent control algorithm. Then, an observer‐based control algorithm is designed based on the low‐and‐high gain feedback technique and the high‐gain observer design methodology. Sufficient conditions are derived to guarantee robust semiglobal swarm tracking for state‐feedback control and output‐feedback control, respectively. Numerical simulations are finally provided to verify the theoretic results.     

耦合调和振子网络系统的联合连通同步

论文分析了耦合调和振子网络系统在联合连通网络拓扑结构下的引导-跟随同步问题.假定每个网络拓扑结构图不连通,但它们在有限时间内能够联合连通,利用代数图论,李雅普诺夫稳定性理论和La Salle不变原理,证明了该系统的同步稳定性.最后,数值模拟进一步验证了所得理论结果的正确性和有效性.     

Synchronization of coupled harmonic oscillators in a dynamic proximity network

In this paper, we revisit the synchronization problems for coupled harmonic oscillators in a dynamic proximity network. Unlike many existing algorithms for distributed control of complex dynamical networks that require explicit assumptions on the network connectivity, we show that the coupled harmonic oscillators can always be synchronized, without imposing any network connectivity assumption. Moreover, we also investigate the synchronization with a leader and show that all harmonic oscillators can asymptotically attain the position and velocity of the leader, again without any assumption on connectivity of the followers. Numerical simulation illustrates the theoretical results.     

Stabilisation of stochastic delayed systems with Lévy noise on networks via periodically intermittent control

ABSTRACT

This paper investigates the stabilisation of stochastic coupled systems with time-varying delays and Lévy noise on networks (SCSTLN) via periodically intermittent control. And here, internal delays, white noise and Lévy noise are considered in the networks. To ensure stability of SCSTLN with a periodically intermittent controller, several simple and useful criteria are obtained by establishing a new differential inequality and using a graph-theoretic approach. The intensity of control is closely related to the coupling strength and the perturbed intensity of white noise and Lévy noise. In particular, the stabilisation of stochastic coupled oscillators with time-varying delays and Lévy noise on a network as a practical application of our theoretical results is studied. Finally, a numerical example about oscillators network is carried out to show the validity and feasibility of our analytical results.     

Consensus of second-order multi-agent systems with nonsymmetric interconnection and heterogeneous delays

In this paper, a consensus algorithm of multi-agent second-order dynamical systems with nonsymmetric interconnection and heterogeneous delays is studied. With the hypothesis of directed weighted topology graph with a globally reachable node, decentralized consensus condition is obtained by applying generalized Nyquist criterion. For the systems with both communication and input delays, it is shown that the consensus condition is dependent on input delays but independent of communication delays.     

一种带时间窗口的双脉冲控制器下的忆阻振荡系统滞同步

在真实的环境中实现复杂忆阻振荡系统的同步时, 因为信息干扰及通信问题, 驱动和响应系统之间总是存在信息传输时滞, 即时滞问题具有普遍性; 另外, 脉冲控制信号的输入总是存在输入误差, 并不能实现精确地输入.本文考虑到上述实际存在的信息传输时滞和脉冲输入误差, 设计了一种比较接近真实情况的、灵活的可以带有不同时间窗口和不同控制增益的双脉冲切换控制器, 并且利用该控制器实现了两个复杂忆阻振荡系统的滞同步.基于Lyapunov稳定性理论、矩阵不等式以及脉冲控制等相关理论, 本文找出了实现一类五阶复杂忆阻振荡系统同步的条件.最后的仿真实验进一步验证了本控制方法的可行性.     

Synchronization of coupled harmonic oscillators with local interaction

This paper studies synchronization of coupled second-order linear harmonic oscillators with local interaction. We analyze convergence conditions over, respectively, directed fixed and switching network topologies by using tools from algebraic graph theory, matrix theory, and nonsmooth analysis. It is shown that the coupled harmonic oscillators can be synchronized under mild network connectivity conditions. Examples are given to validate the convergence conditions. The theoretical result is also applied to synchronized motion coordination of multi-agent systems as a proof of concept.     

Synchronization for an array of coupled stochastic discrete-time neural networks with mixed delays

In this paper, a synchronization problem is investigated for an array of coupled stochastic discrete-time neural networks with both discrete and distributed time-varying delays. By utilizing a novel Lyapunov function and the Kronecker product, it is shown that the addressed stochastic discrete-time neural networks is synchronized if certain linear matrix inequalities (LMIs) are feasible. Neither any model transformation nor free-weighting matrices are employed in the derivation of the results obtained, and they can be solved efficiently via the Matlab LMI Toolbox. The proposed synchronization criteria are less conservative than some recently known ones in the literature, which is demonstrated via two numerical examples.     

Differential coupling contributes to synchronization via a capacitor connection between chaotic circuits

Nonlinear oscillators and circuits can be coupled to reach synchronization and consensus. The occurrence of complete synchronization means that all oscillators can maintain the same amplitude and phase, and it is often detected between identical oscillators. However, phase synchronization means that the coupled oscillators just keep pace in oscillation even though the amplitude of each node could be different. For dimensionless dynamical systems and oscillators, the synchronization approach depends a great deal on the selection of coupling variable and type. For nonlinear circuits, a resistor is often used to bridge the connection between two or more circuits, so voltage coupling can be activated to generate feedback on the coupled circuits. In this paper, capacitor coupling is applied between two Pikovsk-Rabinovich (PR) circuits, and electric field coupling explains the potential mechanism for differential coupling. Then symmetric coupling and cross coupling are activated to detect synchronization stability, separately. It is found that resistor-based voltage coupling via a single variable can stabilize the synchronization, and the energy flow of the controller is decreased when synchronization is realized. Furthermore, by applying appropriate intensity for the coupling capacitor, synchronization is also reached and the energy flow across the coupling capacitor is helpful in regulating the dynamical behaviors of coupled circuits, which are supported by a continuous energy exchange between capacitors and the inductor. It is also confirmed that the realization of synchronization is dependent on the selection of a coupling channel. The approach and stability of complete synchronization depend on symmetric coupling, which is activated between the same variables. Cross coupling between different variables just triggers phase synchronization. The capacitor coupling can avoid energy consumption for the case with resistor coupling, and it can also enhance the energy exchange between two coupled circuits.

     

Partial synchronization and clustering in a system of diffusively coupled chaotic oscillators

We examine the problem of partial synchronization (or clustering) in diffusively coupled arrays of identical chaotic oscillators with periodic boundary conditions. The term partial synchronization denotes a dynamic state in which groups of oscillators synchronize with one another, but there is no synchronization among the groups. By combining numerical and analytical methods we prove the existence of partially synchronized states for systems of three and four oscillators. We determine the stable clustering structures and describe the dynamics within the clusters. Illustrative examples are presented for coupled Rössler systems. At the end of the paper, synchronization in larger arrays of chaotic oscillators is discussed.     

具有脉冲耦合复杂时滞动力网络的同步

考虑了一个具有脉冲耦合的复杂时滞动力网络的同步问题.基于脉冲时滞动力系统扩展的Halanay不等式,给出了网络同步的一个充分条件.所获结果表明,即使网络节点之间仅在一些离散时刻存在瞬时连接,网络仍然能够达到同步.进一步将所得结果应用于一个由混沌FHN神经元振子为动力节点所构成的一个无标度的动力网络,数值仿真结果表明了理...     

Finite‐Time Stabilization of Coupled Systems on Networks with Time‐Varying Delays via Periodically Intermittent Control

In this paper, finite‐time stabilization of coupled systems on networks with time‐varying delays (CSNTDs) via periodically intermittent control is studied. Both delayed subsystems and delayed couplings are considered; the self‐delays of different subsystems in delayed couplings are not identical. A periodically intermittent controller is designed to stabilize CSNTDs within finite time, and the stabilization duration is closely related to the topological structures of networks. Furthermore, two sufficient criteria are developed to ensure CSNTDs under periodically intermittent control can be stabilized within finite time by using an approach that combines the Lyapunov method with Kirchhoff's Matrix Tree Theorem. Then finite‐time stabilization of coupled oscillators with time‐varying delays is given as a practical application and sufficient criteria is obtained. Finally, a numerical simulation is proposed to support our results and show the effectiveness of the controller.     

Event-triggered sampled-data synchronization of complex networks with uncertain inner coupling and time-varying delays

This paper focuses on event-triggered sampled-data synchronization of uncertain complex networks with time-varying coupled delays. First of all, a discrete event-triggered sampled-data control scheme is adopted, which not only makes the state of the system be monitored in discrete time, but also the sampling information is effectively transmitted. The proposed event-triggered mechanism effectively prevents Zeno behavior. In addition, we also use some novel piecewise time-dependent Lyapunov–Krasovskii and Wirtinger inequality to handle the time-varying delays and parameter uncertainties of complex networks. Then, synchronization criteria are given for uncertain complex networks. Finally, the simulation results show that the control scheme can significantly reduce the number of transmitted signals while maintaining the uncertain complex networks synchronization.     

Semi‐global and global containment control of multi‐agent systems with second‐order dynamics and input saturation

This paper considers both semi‐global and global containment control for a second‐order multi‐agent system that is composed by a network of identical harmonic oscillators or double integrators with multiple leaders and input saturation. A distributed low gain feedback algorithm is proposed to solve the semi‐global containment control problem for the network whose topology is directed and initial condition is taken from any a priori given bounded set. In particular, by using a parametric Lyapunov equation approach, M‐matrix properties and algebraic graph theory, an upper bound of the low gain parameter is estimated such that the low gain feedback matrix can be analytically determined without involving numerical computation. Furthermore, under the assumption that the induced subgraph formed by the followers is strongly connected and detail balanced, two linear feedback protocols are designed for coupled harmonic oscillators and coupled double integrators, respectively, to asymptotically achieve the global containment control of the network with any initial condition. Finally, numerical examples are given to illustrate the effectiveness of the theoretical results. Copyright © 2016 John Wiley & Sons, Ltd.     

Adaptive synchronization control design for flexible telerobotics with actuator fault and input saturation

This paper addresses the synchronization control problem of flexible telerobotics with actuator fault, input saturation, and asymmetrical time‐varying delays. A new adaptive antisaturation nonlinear fractional power proportional+damping fault‐tolerant control scheme is designed. With the new control algorithm, faster convergence rate and higher convergence precision can be guaranteed, as compared with the general proportion+damping control method. By choosing Lyapunov‐Krasovskii functional, it shows that the teleoperation system is stable under specific linear matrix inequality conditions. Thus, the allowable maximal transmission delay can be computed with the given controller‐design parameters. To validate the effectiveness of the proposed method, simulations on synchronization control system composed of 2 manipulators (master is rigid, and slave is flexible) are developed. Experiments on the PHANToM Premium 1.5A manipulators are also conducted and numerous experimental results are presented to show the superior performance of the proposed control scheme.     

Formation control of VTOL Unmanned Aerial Vehicles with communication delays

The formation control problem of a team of Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicles (UAVs) with communication delays is addressed. Based on the extraction algorithm presented in Abdessameud and Tayebi (2010a), we propose a new design methodology that simplifies the design of formation control laws with delayed communication for this class of under-actuated systems. Three control schemes are presented that provide delay-dependent and delay-independent results with constant and time-varying communication delays. The stability of the overall closed loop system in each scheme is established using Lyapunov–Krasovskii functionals. The proposed design methodology achieves global results in terms of the position and removes the requirement of the linear-velocity measurements. Simulation results are provided to show the effectiveness of the proposed control schemes.     

Delay-coobservability and its algebraic properties for the decentralized supervisory control of discrete event systems with communication delays

In networked control systems, uncontrollable events may unexpectedly occur at a plant before a proper control command is applied to it due to communication delays. In this paper, we address the problem of decentralized supervisory control under such communication delays based on the C&P (conjunctive and permissive) and D&A (disjunctive and antipermissive) decision architecture. In particular, for the existence of a decentralized supervisor, we present the notion of delay-coobservability of a given language specification and a polynomial-time algorithm for verifying it. In addition, algebraic properties of the delay-coobservability are investigated. We further present a synthesis method of the decentralized supervisor for practical usefulness.