Leader-follower Synchronization Research Articles

Leader-following synchronization for Lur’e networks via dynamic event-triggered control

This paper considers synchronization of Lur’e systems under a dynamic event-triggered framework. To facilitate the study, a novel time-varying sampled-data-related dynamic event-triggered control (ETC) related to fully discrete local information is proposed, which does not require continuous communication among nodes and naturally avoids Zeno behavior. By using the Halanay inequality, a number of sufficient criteria to achieve leader-following synchronization are derived, from which the allowable sampling interval can be calculated. In addition, the introduction of dynamic parameters in event-triggered condition shows better performance in reducing the event-triggered number, since the existing of a negative term in event-triggered condition slows down the rapid growth of triggering threshold. Further, heterogeneous Lur’e networks are investigated. By taking advantage of the boundedness of leaders, quasi-synchronization can be guaranteed in heterogeneous Lur’e networks, which makes the conclusions more general. At last, to show the effectiveness of the derived sampled-data-based dynamic ETC mechanism in both homogeneous and heterogeneous Lur’e networks separately, two simulation examples are presented.

Leader-Following Synchronization Control of Multiagent Systems Under Hybrid Cyber Attacks via Impulsive Control Based on Topology Switching.

This article investigates the leader-following synchronization problem of multiagent systems (MASs) under hybrid cyber attacks, which refers to deception attacks and multichannel independent denial-of-service (DoS) attacks in communication channels. In order to achieve the secure control of MASs under hybrid cyber attacks, a novel impulsive control method based on topology switching is proposed, and a new algorithm for determining impulsive instants is designed. In addition, the cooperative-competitive relationship between agents is also considered, which is more in line with reality. Sufficient conditions for ensuring secure control of MASs and a parametric upper bound on the error vector norm between the agents and the leader are obtained. Finally, the numerical simulation verified the effectiveness of the proposed algorithm.

Cluster Synchronization of Finite-Field Networks.

This technical paper investigates the cluster synchronization of finite-field networks (FFNs) based on the algebraic state space representation. By resorting to the semi-tensor product of matrices, the cluster synchronization of an FFN can be completely converted into the set stability of state trajectory. Then, a necessary and sufficient condition for the cluster synchronization of FFNs is obtained based on the invariant subset and one-step transition matrix. In particular, the obtained results are applicable to check the leader-follower synchronization and group consensus of FFNs. Finally, a numerical example is given to illustrate the feasibility of the obtained results.

Finite-Time Synchronization of Complex Dynamical Networks With Input Saturation.

In the framework of input saturation, this article studies the problem of finite-time synchronization (FTS) of a class of complex dynamical networks. By designing different classes of saturated controllers, two types of FTS criteria, including leader-follower synchronization and leaderless synchronization, are presented, respectively. A potential relationship between the saturation structure, the settling time, and the domain of attraction is established, which is crucial to achieve FTS. It shows that the saturation structure not only affects the estimation of domain of attraction but also possibly changes the settling time for FTS. Two numerical examples are presented to illustrate the effectiveness of the proposed results.

A collective neuroscience lens on intergroup conflict.

How do team leaders and followers synchronize their behaviors and brains to effectively manage intergroup conflicts? Zhang and colleagues offered a collective neurobehavioral narrative that delves into the intricacies of intergroup conflict. Their results underscore the importance of leaders' group-oriented actions, along with leader-follower synchronization, in intergroup conflict resolution.

Containment control of multiple unmanned surface vessels with NN control via reconfigurable hierarchical topology.

This paper investigates the containment control of multiple unmanned surface vessels with nonlinear dynamics. To solve the leader-follower synchronization problem in a containment control system, a hierarchical control framework with a topology reconfiguration mechanism is proposed, and the process of containment control is converted into the tracking of a reference signal for each vessel on its respective target heading by means of the light-of-sight (LOS) guidance. In a control system, the neural networks (NNs) are adopted to consider the uncertainty. In the follower layer, a connectivity controller with a topology reconfiguration mechanism is embedded, to change the converging positions of followers so as to avoid collision within the system, and to maintain the system connectivity when the communication equality is poor. The effectiveness of the hierarchical control framework proposed in this paper is valid by simulation.

Sampled-Data-Based Bipartite Leader-Follower Synchronization of Cooperation-Competition Neural Networks via Interval-Scheduled Looped-Functions

This paper addresses the bipartite leader-follower synchronization (BLFS) of cooperation-competition neural networks (CCNNs) via sampled-data (SD) control. First, the directed signed graph (SG) theory is applied to describe the cooperation and competition interactions, and thus, an appropriate mathematical model is constructed for such kind of multiple CCNNs. Based on the coordinate transformation technique, the main challenges encountered from the Laplacian matrix of the directed SG are circumvented. Then, a tractable error system can be established in the presence of SD control. Two interval-scheduled looped-functions are well-structured by relaxing the requirements of positive definiteness and continuity, respectively. In combination with discrete Lyapunov theory and some inequality techniques, some less conservative criteria are derived to guarantee the BLFS of CCNNs. Compared with the previous analysis methods, a smaller coupling strength or a larger sampling interval can be permitted on the basis of the developed results. Finally, two examples are presented to verify the effectiveness and advantages of the obtained results.

Leader–follower synchronization of networked multi‐agent systems via hybrid protocols

AbstractThis paper studies the leader–follower synchronization problem of complex‐valued networked multi‐agent systems with time‐delay. A new hybrid protocol including a continuous‐time protocol which is based on the interaction topology of follower agents and a pinning delayed impulsive control protocol is proposed. By employing the Lyapunov functional method in complex domains and the mathematical analysis technique, several delay‐dependent leader–follower synchronization criteria are established that take into account various sizes of delays. Particularly, our result shows that leader–follower synchronization of delayed complex‐valued networked multi‐agent systems can be achieved even if the proposed hybrid protocol is being subject to relatively large impulse delays. A numerical example is provided to illustrate the effectiveness of the theoretical results.

Asymptotic pinning synchronization of nonlinear multi-agent systems: Its application to tunnel diode circuit

This work proposes a pinning state-feedback control technique for synchronizing non-linear multi-agent systems (MASs) with time delays. A collection of switching-directed graphs describes the communication exchanges between all of the agents. The challenge of asymptotic stability analysis for some error systems is translated into the construction of a leader-following synchronization of the relevant MASs. The closed-loop system could be acquired by building a convenient Lyapunov–Krasovskii functional (LKF) that has two integral terms, and by using Kronecker product qualities combined with matrix inequality techniques. When these conditions are met, a state-feedback pinning controller can be built with linear matrix inequalities (LMIs), which can be derived easily from a number of efficient optimization algorithms. Further, the performance of the proposed control design system is verified based on a tunnel diode circuit (TDC) by numerical simulations.

Saturated and asymmetric saturated impulsive control synchronization of coupled delayed inertial neural networks with time-varying delays

This paper considers control systems with impulses that are saturated and asymmetrically saturated which are used to examine the synchronization of inertial neural networks (INNs) with time-varying delay and coupling delays. Under the theoretical discussions, mixed delays, such as transmission delay and coupling delay are presented for inertial neural networks. The addressed INNs are transformed into first order differential equations utilizing variable transformation on INNs and then certain adequate conditions are derived for the exponential synchronization of the addressed model by substituting saturation nonlinearity with a dead-zone function. In addition, an asymmetric saturated impulsive control approach is given to realize the exponential synchronization of addressed INNs in the leader-following synchronization pattern. Finally, simulation results are used to validate the theoretical research findings.

Exponential Synchronization of Hyperbolic Complex Spatio-Temporal Networks with Multi-Weights

This paper deals with the leader-following synchronization of first-order, semi-linear, complex spatio-temporal networks. Firstly, two sorts of complex spatio-temporal networks based on hyperbolic partial differential equations (CSTNHPDEs) are built: one with a single weight and the other with multi-weights. Then, a new distributed controller is designed to address CSTNHPDE with a single weight. Sufficient conditions for the synchronization and exponential synchronization of CSTNHPDE are presented by showing the gain ranges. Thirdly, the proposed distributed controller addresses of CSTNHPDE with multi-weights, and gain ranges are obtained for synchronization and exponential synchronization, respectively. Finally, two examples show the effectiveness and good performance of the control methods.

Synchronized control of multiple electrohydraulic systems with terminal sliding mode observer under parametric uncertainty and external load

The leader-following synchronization control strategy is proposed for multiple electro-hydraulic systems (MEHS) to realize all the follower outputs of electrohydraulic systems synchronized to a virtual leader demand. Due to existed lumped uncertainties generated by some uncertain errors of hydraulic parameters and unascertainable external load disturbance, the synchronization control performance of MEHS will be degraded by using many common controllers. In this study, a terminal sliding mode observer (TSMO) is adopted in the MEHS to estimate the lumped uncertainties such that guarantees uncertainty estimated errors convergence to zero in a finite time. Then a synchronized controller of MEHS is designed by backstepping iteration and Lyapunov technique to guarantee the output cylinder position of every EHS tracking the virtual leader demand. Finally, the feasibility and effectiveness of the designed TSMO and the proposed synchronized control strategy are verified via simulation and experiment.

Bipartite leader-following synchronization of delayed incommensurate fractional-order memristor-based neural networks under signed digraph via adaptive strategy

In this work, an adaptive controller, formulated as linear feedback controls plus nonlinear parts, is synthesized to achieve bipartite leader-following synchronization of delayed incommensurate fractional-order memristor-based neural networks (FMNNs), in which follower FMNNs are linearly coupled under a signed digraph. The salient features of this research lie in two aspects: (1) the assumption on time-varying delays is very weak, since it neither requires boundedness of delays nor restricts the differentiation of time delay functions; (2) the adaptive controller contains no delay term, and it is feasible for both bounded and unbounded activation functions. As the preparatory work for stability analysis of the controlled synchronization error system, the ready-made results on delayed incommensurate fractional-order linear positive systems, especially stability condition and comparison principle, are perfected by relaxing premises of time-varying delays. Besides, a group of differential inclusion inequalities are established as a powerful aid in scaling the bipartite synchronization error system. More relevantly, an algebraic synchronization criterion, formulated in terms of coupling strength, inner coupling matrix, Laplacian matrix and FMNN system parameters, is proved with the benefit of vector Lyapunov function and positive system theory. With the controller utilized, linear feedback controls can be exerted merely on partial neurons of some selected FMNNs, which is exemplified by numerical simulations.

Fixed-time leader-following synchronization in delayed network via non-chattering nonlinear control

The fixed-time leader-following synchronization in a non-identical delayed network via non-chattering nonlinear control is investigated. By introducing a function of control error, a continuous and differential controller is constructed without using the sign function and absolution of the error. The sufficient conditions are then established to guarantee that synchronization errors converge exactly to zero within a fixed time interval. The proposed approach provides a high convergence for the network accurately tracking the trajectory of the leader. More importantly, a tighter bound for the settling time is obtained and the chattering effects are eliminated. The numerical simulations are conducted to illustrate the effectiveness of theoretical analysis.

Bipartite leader-following synchronization of fractional-order delayed multilayer signed networks by adaptive and impulsive controllers

This article addresses the problem of bipartite leader-following synchronization of fractional-order delayed multilayer signed networks. It is worth emphasizing that fractional dynamics and multiple connections between nodes with multiple time delays are considered into signed networks. In our main results, adaptive control (continuous control) and impulsive control (discontinuous control) are both designed to reach the bipartite leader-following synchronization of the underlying networks. In addition, a Halanay inequality of fractional version is established. With the help of it, by using signed graph theory and Lyapunov method, some bipartite synchronization criteria are derived under the Lyapunov-type theorems and coefficients-type theorems. Then, as an application of theoretical results, the bipartite leader-following synchronization of fractional-order coupled Chua’s circuits modeled on delayed multilayer signed networks is considered. Finally, two numerical examples are exhibited to exemplify the usefulness and feasibility of the theoretical results.

Synchronous control for multiple electrohydraulic actuators with feedback linearization

Based on some research of electrichydraulic servo system (EHSS), the synchronous control problem of multiple electrohydraulic actuators (MEHAs) is investigated to guarantee the MEHAs’ system stability and leader-following synchronization with third-order nonlinear dynamics and unknown external load. Firstly, the EHA model is linearized by Lie derivatives technique to obtain the third-order linear isomorphic model of MEHAs with unknown external load. Then the disturbance observer is adopted to estimate unknown external load caused by the driven force of mechanical plant. Meanwhile, the state-feedback matrix is firstly designed by pole placement technique to guarantee the feedback linearization model Hurwitz. Furthermore, the synchronous controller is designed by Lyapunov technique and LMI to guarantee that n EHAs follower states synchronize the leader state with arbitrarily small zeros neighborhood under directed spanning tree. The effectiveness of the synchronous controller is verified by both comparative simulation and experimental bench.

Anti-disturbance leader–follower synchronization control of marine vessels for underway replenishment based on robust exact differentiators

This paper considers the leader–follower synchronization control of under-actuated marine vessels for underway replenishment. An integrated guidance and control method is presented to achieve the underway replenishment operations despite of unknown model uncertainties, external disturbances, and unknown velocities of the leader vessel. Specifically, a velocity observer based on a robust exact differentiator (RED) is firstly designed to estimate the unknown velocity of the leader vessel. Next, a finite-time light-of-sight guidance law based on the velocity observer is developed to synchronize the follower vessels with the leader vessel. Then, two disturbance observers based on REDs are designed to estimate the total disturbances composed of model uncertainties and external disturbances at the kinetic level. With the aid of the RED-based disturbance observers, an anti-disturbance nonlinear control law is presented to track the desired guidance signals in finite time. The tracking errors of the closed-loop system are proved to be ultimately uniformly bounded via Lyapunov stability theory. Finally, an example is utilized to illustrate the effectiveness of the proposed anti-disturbance synchronization control method for multiple under-actuated marine vessels.

Event-triggered leader-following synchronization of delayed dynamical networks with intermittent coupling

Event-triggered leader-following synchronization of delayed dynamical networks with intermittent coupling

Leader-Follower Synchronization of a Network of Boundary-Controlled Parabolic Equations With In-Domain Coupling

In this letter, we study the leader-synchronization problem for a class of partial differential equations with boundary control and in-domain coupling. We describe the problem in an abstract formulation and we specialize it to a network of parabolic partial differential equations. We consider a setting in which a subset of the followers is connected to the leader through a boundary control, while interconnections among the followers are enforced by distributed in-domain couplings. Sufficient conditions in the form of matrix inequalities for the selection of the control parameters enforcing exponential synchronization are given. Numerical simulations illustrate and corroborate the theoretical findings.

Distributed Robust Synchronization Control of Multiple Heterogeneous Quadcopters with An Active Virtual Leader*

This paper studies leader-following synchronization control of a group of multiple quadrotor unmanned aerial systems (UASs). A robust distributed scheme is developed to maintain the attitude motions of UASs with an active virtual leader. Complicated settings are considered in the design, where the topology is in a directed graph, and only one or some agents are connected to the leader. UASs can have different dynamic parameters. Also, some time-varying disturbances are added to the closed-loop system. A control protocol containing a robust term is proposed to each UAS to achieve asymptotic consensus. A rigorous mathematical proof and numerical example are presented to demonstrate the effectiveness of our scheme.