General Linear Multi-agent Systems Research Articles

Leader Selection in Impulsive Multiagent Systems With Switching Topologies.

In leader-follower multiagent systems (MASs), seeking an efficient scheme to select a set of agents as leaders is important for realizing the expected cooperative performance. In this article, the problem of minimal leader selection is investigated for impulsive general linear MASs with switching topologies. This study focuses on selecting a set of agents as leaders that receive information from a reference signal directly, while minimizing the number of leaders, subject to consensus tracking performance. First, adopting the average dwell time technique and a time-ratio constraint, an explicit criterion for consensus tracking is derived as prepreparation for leader selection. Second, applying the submodular optimization framework, leader selection metrics are established based on the derived criterion. Third, employing the greedy rule, an efficient leader selection scheme is presented according to the established metrics. The scheme comprises two polynomial-time algorithms that return selected leader sets within a logarithmic bound of the optimum. Finally, the effectiveness of the developed leader selection scheme is verified using an illustrative example.

Optimal Consensus Control for Continuous-Time Linear Multiagent Systems: A Dynamic Event-Triggered Approach.

This article investigates the optimal consensus problem for general linear multiagent systems (MASs) via a dynamic event-triggered approach. First, a modified interaction-related cost function is proposed. Second, a dynamic event-triggered approach is developed by constructing a new distributed dynamic triggering function and a new distributed event-triggered consensus protocol. Consequently, the modified interaction-related cost function can be minimized by applying the distributed control laws, which overcomes the difficulty in the optimal consensus problem that seeking the interaction-related cost function needs all agents' information. Then, some sufficient conditions are obtained to guarantee optimality. It is shown that the developed optimal consensus gain matrices are only related to the designed triggering parameters and the desirable modified interaction-related cost function, relaxing the constraint that the controller design requires the knowledge of system dynamics, initial states, and network scale. Meanwhile, the tradeoff between optimal consensus performance and event-triggered behavior is also considered. Finally, a simulation example is provided to verify the validity of the designed distributed event-triggered optimal controller.

Resilient Time-Varying Formation Tracking Control for General Linear Multiagent Systems With a Nonautonomous Leader and Adversarial Followers.

This article is concerned with resilient formation tracking problems for general linear multiagent systems, where the leader's control input is unavailable to all the followers and partial followers' behaviors are malicious due to the node attacks. Despite the presence of the nonautonomous leader and the adversarial followers, the remaining benign followers are still expected to track the leader's trajectory with the prescribed time-varying formation. To this end, a resilient scheme comprising an attack detection and isolation strategy and a formation tracking protocol is proposed. The detection strategy enables every benign follower to identify its adversarial neighbors with two-hop communication information, as long as the underlying topology meets given conditions. Then, the detected adversarial agents are directly removed to avoid the spread of their influence, which induces a new problem called node loss. To accommodate possible node loss events, the designed tracking protocol is independent of certain global knowledge, and its convergence is demonstrated by means of the impulsive Lyapunov functions. Finally, the proposed resilient scheme is verified by two simulation examples.

Observer-based time-varying formation-containment tracking of general linear multi-agent systems with input saturation

In this article, we study the time-varying formation-containment (TVFC) tracking problem for linear multi-agent systems (MASs) and take the input saturation problem of the systems into account. An observer-based TVFC tracking protocol is proposed. It has been proven that the real leaders can realize the expected formation and track the virtual leader’s trajectory, and followers can get into the convex envelope spanned by the leaders. In addition, to avoid unexpected large chattering caused by nonzero input, we propose a continuous protocol. Under this protocol, each error is uniformly ultimately bounded and is able to converge to any small zero neighborhood. At the end, the feasibility of the TVFC theory is demonstrated by simulation examples.

Distributed Dynamic Event-Triggered Consensus Protocol for General Linear Multiagent Systems Without Accurate System Information.

This study focuses on distributed event-triggered consensus control under the scenario where only inaccurate agent model information is available. By designing a novel triggering error, a distributed dynamic event-triggered consensus (DETC) protocol is proposed for multiagent systems (MASs) with general linear dynamics over digraphs, without accurate a priori information of agent models. To improve the efficiency of the dynamic triggering law, a mixed triggering threshold is designed with a resilient function integrated to further enlarge interevent intervals. Within the proposed DETC protocol, the computational cost is significantly reduced especially for MASs with nonsparse and high-dimensional agent system matrices. In addition, for each individual agent, the states of neighboring agents used for triggering detections or controller updates are required in an on-demand (instead of continuous) way, which preserves communication resources and facilitates practical implementation. The feasibility of the designed DETC protocol is corroborated by rigorous theoretical analysis on consensus convergence and Zeno behavior exclusion. Finally, simulations are shown to demonstrate the effectiveness of the studied theory.

Fixed-Time Consensus Control of General Linear Multiagent Systems

Fixed-Time Consensus Control of General Linear Multiagent Systems

Edge-based event-triggered consensus control of multi-agent systems against DoS attacks

This article focuses on the security consensus control for general linear multi-agent systems against denial of service (DoS) attacks. In particular, an edge-based event-triggered protocol is proposed to reduce unnecessary information transmission through energy-limited and fragile networks, where the dynamic event-triggered condition is designed by introducing internal dynamic variables. The state of agents is dynamically estimated, and the control inputs based on estimated value can offer better control performance. It is demonstrated that under DoS attacks, the security consensus of multi-agent systems can be realised without Zeno behaviour by adopting the dynamic edge-based event-triggered control strategy. Finally, a numerical simulation example is included to prove the effectiveness of the proposed method.

Fully distributed observer-based scaled consensus of multi-agent systems with actuator saturation and edge-based event-triggered communication

This work uses an edge-based event-triggered technique to study the adaptive scaled consensus of general linear multi-agent systems with actuator saturation and unmeasurable internal states. By proposing an edge-based event-triggered scaled algorithm, constructing an improved Lyapunov function, and introducing a low-gain feedback technique, the difficulties generated by actuator saturation and scaling property are overcome, and a triggering condition based on the triggering function is obtained, under which the scaled consensus is achieved, and the Zeno behavior is excluded. This work’s results are more flexible than existing results; in other words, triggering numbers and convergence rates are adjusted in this work. Finally, several examples are proposed to verify the results and their interesting characteristics.

Observer-based event-triggered time-varying formation control of linear multi-agent systems with distributed infinite delays

Compared with bounded delays, distributed infinite delays are more general in practical systems. Event-triggered control can effectively reduce energy consumption and communication costs. This paper addresses time-varying formation control of general linear multi-agent systems with distributed infinite delays in both of their inputs and outputs. An observer-based event-triggered formation control protocol considering distributed infinite delays is proposed, which is related to the combined observed information and some formation compensation signals at triggering time instants. By utilizing inequality techniques, the desired time-varying formation can be implemented while Zeno-behavior is excluded. Some numerical simulations are carried out for demonstrating the validity of theoretical results.

Secure Fully Distributed Event-Triggered Consensus of Multi-Agent Systems Against Distributed Sequential Scaling Attacks

This article is concerned with the secure fully distributed event-triggered consensus problem of general linear multi-agent systems subject to distributed sequential scaling (DSS) attacks. First, a generic DSS attack model is proposed, which enables different attack strategies in terms of scaling factors, attack frequency and duration to be incorporated in various communication channels. Different from existing attack models, the DSS attack is a kind of scaling attacks in which attack sequences are characterized by the sequential attacks and with distributed attack strategies for different attack objectives. To resist the adverse effects of such DSS attacks and further reduce the unnecessary communication consumption of each communication channel, a channel-based dynamic event-triggered mechanism is next presented. Moreover, a fully distributed event-triggered consensus control protocol is developed such that the dependence of any global information of the network topology can be eliminated. Formal analysis criteria on the asymptotic convergence of the resultant consensus errors and Zeno-freeness are then derived, where the relationship of the triggering parameters, distributed scaling factors and attack constraints is explicitly expressed. Furthermore, an offline algorithm without any global information is provided to determine both the adaptive consensus protocol gain matrices and the triggering parameters. Therefore, the parameters calculated by this algorithm are applicable to multi-agent systems of different scales, which also confirms the flexibility and scalability of the proposed fully distributed event-triggered consensus control protocol. Finally, two simulation examples involving different scales of intelligent vehicles are given to validate the efficacy of the obtained theoretical results.

Specified-Time Practical Consensus for General Linear Multi-Agent Systems With Switching Mechanism

Specified-Time Practical Consensus for General Linear Multi-Agent Systems With Switching Mechanism

Fully Distributed Algorithms for Constrained Nonsmooth Optimization Problems of General Linear Multiagent Systems and Their Application

Fully Distributed Algorithms for Constrained Nonsmooth Optimization Problems of General Linear Multiagent Systems and Their Application

Composite Output Consensus Control for General Linear Multiagent Systems With Heterogeneous Mismatched Disturbances

Composite Output Consensus Control for General Linear Multiagent Systems With Heterogeneous Mismatched Disturbances

Fully Distributed Observer-Based Leader-Following Consensus of Linear Multiagent Systems by Adaptive Dynamic Event-Triggered Schemes.

The leader-following consensus issue for general linear multiagent systems (MASs) is investigated under event-triggered communication (ETC). Based on the output measurement of agent, two novel adaptive dynamic event-triggered (ADET) strategies for synchronous and asynchronous ETC are proposed, in which adaptive triggering parameters and time-varying threshold are introduced. Simultaneously, the corresponding control protocols are developed under the ADET strategies. Different from most existing relevant results, triggering mechanisms and control protocols do not require global information and network size, ensuring a fully distributed implementation. The asynchronous ETC, in particular, gives a flexible for transmitting information. The effectiveness of ADET strategies is further analyzed and discussed, and a comparative analysis between observer-based and state-based ADET algorithms is provided, highlighting their efficiencies and applications. Theoretical claims are substantiated with a simulative example that demonstrates the practical effectiveness of the proposed strategies.

Fully distributed consensus of linear multi-agent systems via dynamic event-triggered control

This paper investigates the fully distributed consensus control problem for general linear multi-agent systems via dynamic event-triggered scheme. To address the need to reduce network communication burdens and avoid involving any global features of multi-agent networks, a novel fully distributed controller based on the open-loop state estimator of agents is presented. To improve anti-interference ability and practicability of the proposed approach, an event-triggered strategy which can guarantee a precise lower bound of triggering intervals for each follower is designed with a virtual internal variable. Then, the stability of the multi-agent systems is analyzed without any global network information. Several simulation experiments are conducted to illustrate theoretical results.

Human-in-the-Loop Formation-Containment Control for Multiagent Systems: An Observer-Based Distributed Unknown Input Reconstruction Method

This paper studies the human-in-the-loop time-varying formation-containment tracking (TVFCT) control problem of general linear multiagent systems (MASs). The MASs consist of a non-autonomous tracking leader, multiple formation leaders and followers, and all agents are subject to unknown disturbances. A human operator is deployed to supervise and regulate the entire team by sending a command signal to the tracking leader. The control input of the tracking leader should be combined with the human operator but not available to other agents. First, a local observer associated with each agent is constructed to provide asymptotic state estimation, in which the observer error system is disturbance-free. Also, interval observers are established for the neighborhood TVFCT errors, where the disturbance of the current agent is aggregated with the disturbances and input signals of its neighbors into an unknown input. Meanwhile, a distributed asymptotic unknown input reconstruction (UIR) mechanism is proposed that decouples the control input of the current agent. The consequent human-in-the-loop TVFCT control protocol is designed by combining the local observer and distributed UIR scheme. Finally, the theoretical results are verified in multi-robot formation-containment control.

Free-Weighting Matrix Approach for Event-Triggered Cooperative Control of Generic Linear Multi-agent Systems: An Application for UAVs

Free-Weighting Matrix Approach for Event-Triggered Cooperative Control of Generic Linear Multi-agent Systems: An Application for UAVs

The Binary Distributed Observer Approach to the Cooperative Output Regulation of Linear Multiagent Systems

In this note, the cooperative output regulation problem of general heterogeneous linear multi-agent systems with binary constraints is studied. To speed up the convergence rate, the binary distributed observer is proposed only utilizing sign of the relative state instead of using full relative information. Under some mild conditions, the binary distributed observer can estimate the state of the leader system exponentially in finite time sense. The leader system can generate various reference signals such as step functions, sinusoidal functions or their combinations. Furthermore, both state and output feedback control protocols are synthesized to solve the problem. An illustrative example is presented to support the feasibility of the proposed framework.

A fully distributed event-Triggered control approach to leader-following consensus of multiagent systems

This paper investigates the leader-following consensus problem for general linear multiagent systems under a fully distributed manner. To avoid using the global information of the communication network, two node-based adaptive parameters are designed and introduced to the fully distributed event-based control law. Such a protocol is more scalable and flexible for large-scaled and complex networked system, such as microgrids or multiple unmanned vehicles. A novel event-triggered rule is presented, and an internal dynamic variable is introduced in it to further cut down the triggering times and save the communication resources. A well-designed Lyapunov function candidate is constructed to not only ensure the convergence of the close-looped systems but also avoid using the eigenvalue of Laplacian matrix in the dynamic variable. Moreover, it is proved that the designed event-triggered conditions can avoid the Zeno behaviour. Finally, a simulation example based on a group of unmanned intelligent vehicle systems is provided to demonstrate the validity of the designed control method.

Secure Consensus of Multiagent Systems With DoS Attacks via Fully Distributed Dynamic Event-Triggered Control

This article investigates the secure consensus problem of general linear multiagent systems with denial-of-service (DoS) attacks. Owning to the existence of DoS attacks, it is challenging to investigate the event-triggered control of multiagent systems in a fully distributed manner. This article presents a novel dynamic event-triggered mechanism to alleviate the limited communication resources. Moreover, the designed mechanism is fully distributed and scalable owing to the introduction of some adaptive coupling weights. Since the DoS attacks have been considered in the event-triggered rule design, a novel adaptive parameter with an additional exponential term is adopted to deal with DoS attacks. The Lyapunov design also introduces such a term for the subsequent stability analysis. Sufficient conditions guaranteeing the asymptotic consensus of the studied system are developed in light of the controller’s parameters, duration, and frequency of the DoS attacks. Strict proof is provided to demonstrate that a secure consensus can be reached effectively under the proposed control mechanism. Furthermore, it is shown that the Zeno behavior can be excluded from the designed triggering mechanism. Finally, simulations on a multiagent system consisting of interconnected unmanned intelligent vehicles are conducted to verify the results.