Scaled Group Consensus in Multiagent Systems With First/Second-Order Continuous Dynamics

Group consensus of multi-agent systems with hybrid characteristics and directed topological networks

In this paper, the group consensus problem is investigated for multi-agent systems (MASs) with hybrid characteristics and directed topological networks. Firstly, the dynamical model of hybrid multi-agent system (MAS) is constructed, which includes discrete time agents and continuous time agents. A class of distributed control protocols are put forward for hybrid MASs. Then, under fixed and directed topological networks, sufficient and necessary conditions for the realization of group consensus are provided on basis of matrix theory and graph theory. Finally, simulations examples are given to further verify the validity of our theoretical results.

On Relative-Output Feedback Approach for Group Consensus of Clusters of Multiagent Systems

In this article, the group consensus problem is addressed for a network of multiagent systems (MASs). Unlike in existing literature, where a relative-state feedback-based distributed control input is used to achieve group consensus, this work aims at designing a relative-output-based distributed control law to achieve the same goal. To that effect, the Lyapunov stability theory is used to formulate the sufficient and necessary conditions for the existence of such a feedback controller and then separate conditions have been included for its design. In addition to that, a new linear matrix inequality is explored to choose the intracluster coupling strengths to ensure group consensus. In this article, the relative-output-based control approach is investigated for both the leaderless and the leader-following frameworks of the group consensus problem, and the theoretical findings presented are validated using numerical examples and simulation results.

Sliding-Mode-Based Admissible Consensus Tracking of Nonlinear Singular Multiagent Systems Under Jointly Connected Topologies

The admissible consensus tracking problem of nonlinear singular multiagent systems (SMASs) with time-varying delay, uncertainties, and external disturbances under jointly connected topologies is investigated in this article. First, the sliding-mode control (SMC) is applied to effectively reduce the adverse effects of uncertainties and nonlinearities of systems. Then, by the combination of admissible analysis, the Cauchy convergence criterion, and SMC, the sufficient conditions for the admissible consensus tracking and disturbance rejection of SMASs under jointly connected topologies are provided. Furthermore, a distributed SMC law is designed such that the sliding-mode dynamics trajectories reach the sliding surface in finite time. Finally, the simulation results are utilized to indicate the effectiveness of the presented methods.

H∞ Scaled Consensus for MASs With Mixed Time Delays and Disturbances via Observer-Based Output Feedback

In this article, the H_∞ scaled consensus control problem for multiagent systems in the presence of external disturbances and mixed time delays in both input and Lipschitz nonlinearity is investigated. First, a state observer is introduced for each agent based on the output information of the agent. Then, a scaled consensus protocol is proposed via a truncated predictor output-feedback method, which can deal with the input delay. The integral terms with the mixed time delays that are contained in the transformed systems are analyzed by using the Lyapunov-Krasovskii functionals method, and sufficient conditions are obtained to achieve scaled consensus with guaranteed H_∞ performance. An iterative procedure is utilized to calculate the linear matrix inequality. By this, the feedback gain and observer gain are then designed. Finally, a simulation example is provided to illustrate the effectiveness of the theoretical results.

Finite-Time Observer-Based Leader-Following Consensus for Nonlinear Multiagent Systems With Input Delays

This article studies the finite-time observer-based leader-following consensus problem for a class of nonlinear multiagent systems with nonuniform time-varying input delays. Existing works usually assume that input delays are the same constants and the input of the leader is available for each follower. In this article, we propose a new distributed consensus algorithm to relax the conservative condition. A novel finite-time distributed observer is designed for each follower, which can accurately estimate the state information of the leader in a setting time. By means of the observer, the distributed controller is proposed for each follower, and it depends only on the state information of the follower and the estimated-state information of its neighbor agents. Based on the Lyapunov stability theory, it is strictly proved that all agents can achieve a consensus. Finally, the effectiveness of the theoretical results is verified by numerical simulation on a group of single-link manipulators.

Reliable cooperative control and plug-and-play operation for networked heterogeneous systems under cyber-physical attacks

This paper considers a reliable cooperative control and plug-and-play operation problem in networked heterogeneous systems (NHSs), and focuses on the scenario subjected to physical attack-induced actuator failures/uncertainties and Denial-of-Service (DoS) attacks on communication channels between physical nodes. To solve it, a new self-feedback control with an adaptive integral sliding-mode compensator is developed. The new one configures each heterogeneous system under the malicious actuator failures/uncertainties to be passivity-short (PS). The PS index quantifies the impact of each attacked heterogeneous dynamics on their networked operations. Furthermore, based on cloud networks, a novel network-level distributed control is proposed. It improves robustness of the systems against DoS with no frequency and duration constraints. And then, a technical condition is presented with the aid of the impact equivalence principle. Under the condition, the self-feedback and network-level controls designed separately but performed together ensure the leader-follower consensus and plug-and-play operation of the attacked NHSs. Finally, the effectiveness of the proposed method is verified by flight control systems.

Adaptive Consensus Control of Linear Multiagent Systems With Dynamic Event-Triggered Strategies

This paper is concerned with event-triggered consensus of general linear multiagent systems (MASs) in leaderless and leader-following networks, respectively, in the framework of adaptive control. A distributed dynamic event-triggered strategy is first proposed, in which an auxiliary parameter is introduced for each agent to regulate its threshold dynamically. The time-varying threshold ensures less triggering instants, compared with the traditional static one. Then under the proposed event-triggered strategy, a distributed adaptive consensus protocol is formed including the updating law of the coupling strength for each agent. Some criteria are derived to guarantee leaderless or leader-following consensus for MASs with general linear dynamics, respectively. Moreover, it is proved that the triggering time sequences do not exhibit Zeno behavior. Finally, the effectiveness of the proposed dynamic event-triggered control mechanism combined with adaptive control is validated by two examples.

Fault-Tolerant Consensus Tracking Control for Linear Multiagent Systems Under Switching Directed Network

In this paper, for linear leader-follower networks with multiple heterogeneous actuator faults, including partial loss of effectiveness fault and actuator bias fault, a cooperative fault-tolerant control (CFTC) approach is developed. Assume that the interaction network topology among all nodes is a switching directed graph. To address the difficulty of designing the distributed compensation control laws under the time-varying asymmetrical network structure, a novel distributed-reference-observer-based fault-tolerant tracking control approach is established, under which the global tracking errors are proved to be asymptotically convergent in the presence of actuator failures. First, by constructing a group of distributed reference observers based on neighborhood state information, all followers can estimate the leader's state trajectories directly. Second, a decentralized adaptive fault-tolerant tracking controller via local estimation is designed to achieve the global synchronization. Furthermore, the reliable coordination problem under switching directed topology with intermittent communications is solved by utilizing the presented CFTC approach. Finally, the effectiveness of the proposed coordination control protocol is illustrated by its applications to a networked aircraft system.

Consensus Tracking for Heterogeneous Interdependent Group Systems

This paper is concerned with the consensus tracking problem for heterogeneous interdependent group systems with fixed communication topologies. First, the interdependent model of the heterogeneous system is built from the perspective of the difference of the individual characteristic and the difference of the subgroup topology structure. A class of distributed consensus tracking control protocol is proposed for realizing the consensus tracking of the heterogeneous interdependent group system via using local information. Then, for fixed communication topologies, some corresponding sufficient conditions are given to ensure the achievement of the consensus tracking. Two parameters are defined, which denote, respectively, the proportion of interdependence individual and the redundancy of interdependence. The effects of these parameters are analyzed on the consensus tracking of group systems. Numerical simulations are provided to illustrate the effectiveness of the theoretical analysis.