Output Regulation Of Multi-agent Systems Research Articles

Hybrid Event-Triggered Cooperative Output Regulation of Multiagent Systems With Unreliable Communication Link.

This article studies the event-triggered cooperative output regulation problem of heterogeneous multiagent systems with external disturbances and unreliable communication link (i.e., packet losses occur intermittently). A novel hybrid event-triggering mechanism (ETM) is proposed, which imposes a strictly positive lower bound for triggering intervals, and an internal variable with jump dynamics is introduced to design triggering condition. A hybrid model is constructed to describe the closed-loop system with both flow and jump dynamics. Then, based on the hybrid model, Lyapunov-based consensus analysis, hybrid ETM design, and robust performance analysis results are developed. Compared with the existing results, the minimum triggering interval (MTI) can be prespecified, and Zeno behavior is ensured to be excluded no matter there exist disturbances or not, which is useful for control implementation. Besides, the packet losses are allowed to be nonidentical, that covers identical packet losses as a special case. Moreover, the tradeoff between MTI and the number of maximum-allowable successive packet losses is explicitly given. Finally, simulation results are provided to show the effectiveness of the proposed method.

Distributed Event-Triggered Cooperative Output Regulation for Multiagent Systems

Distributed Event-Triggered Cooperative Output Regulation for Multiagent Systems

Data-driven cooperative output regulation of multi-agent systems under distributed denial of service attacks

Data-driven cooperative output regulation of multi-agent systems under distributed denial of service attacks

A fully distributed adaptive event-triggered control for output regulation of multi-agent systems with directed network

This paper considers the cooperative output regulation problem for heterogeneous linear multi-agent systems via an event-triggered control strategy for the directed graph. First, to cancel the requirement of continuous update of the control rule, a novel distributed event-triggered control protocol such that each agent can determine when to update the control rule asynchronously, where the Zeno behavior is strictly ruled out based on the contradiction. Later, to make the multi-agent systems more flexible, based on the adaptive control technology, the cooperative output regulation problem of heterogeneous linear multi-agent systems can be solved in a fully distributed manner, where the global information, such as the number of agents or the eigenvalues of Laplacian matrix, is no longer needed. Furthermore, the considered communication network is a more general directed network, in which the minimum communication channel of the directed network is halved compared with the undirected case. Finally, the effectiveness of the proposed control strategy is verified on a group of heterogeneous agents.

Adaptive Secure Practical Fault-tolerant Output Regulation of Multiagent Systems With DoS Attacks by Asynchronous Communications

The secure practical fault-tolerant output regulation of multiagent systems (MASs) with denial-of-service (DoS) attacks is considered in this paper. Different from most existing output regulation problems: 1) The leader matrix is only known to a part of followers; 2) The communication networks are unreliable and there exist DoS attacks; 3) Actuator faults exist in the MASs. Firstly, to overcome the impact of DoS attacks, the adaptive edge-event-triggered observer is designed to estimate the leader's matrix and state. The novel edge-event-triggered mechanism enables asynchronous intermittent communication between agents, and the adaptive learning rate makes the observer design independent of the global information for the communication topology. Secondly, in order to compensate for the impact of actuator faults on system stability, a novel resilient adaptive event-triggered fault-tolerant controller is designed, and it has zero-order holder (ZOH) characteristics and avoids chattering phenomenon. Finally, two simulation examples well show the effectiveness of our developed methods.

Distributed Observer Approach to Cooperative Output Regulation of Multi-Agent Systems Without Exchange of Controller States

Distributed Observer Approach to Cooperative Output Regulation of Multi-Agent Systems Without Exchange of Controller States

A Lyapunov Approach to Robust Cooperative Output Regulation of Multiagent Systems Under Infinite Communication Delays

This article investigates the robust cooperative output regulation problem of heterogeneous uncertain linear multiagent systems with switching topologies and infinite distributed communication delays. A novel distributed observer is proposed for each agent to estimate the state of the so-called exosystem by taking consideration of both switching topologies and infinite distributed communication delays. A distributed output feedback controller is then developed based on the internal model principle and the estimated state without using the prior knowledge of communication delays. It is shown via the newly developed Lyapunov-like method that the robust cooperative output regulation problem can be solved under some mild assumptions. Finally, a numerical example is given to demonstrate the effectiveness of the proposed controller.

Fully Distributed Event-Triggered Cooperative Output Regulation of Multi-Agent Systems under Jointly Connected Digraphs

This paper addresses the cooperative output regulation problem of heterogeneous linear multi-agent systems (MASs) with <i>jointly connected digraphs</i> under the assumption that the exosystem matrix is only known by the neighbors of the exosystem. First, a novel event-based adaptive distributed observer with time-dependent power functions as the event-triggering threshold is proposed to estimate the exosystem matrix and the exogenous signal simultaneously. A new analytical method based on the weighted mean-value theorem for integrals and Bellman-Gronwall lemma is developed to prove the estimation errors converge to zero asymptotically. Second, a distributed dynamic control law is proposed based on the event-based adaptive observer, and it is shown that the tracking errors of the resulting closed-loop system converge to zero asymptotically. Two distinctive advantages of this work are (i) the event-triggered control (ETC) protocol is fully distributed, and (ii) a positive minimum inter-event time (MIET) is explicitly given so that Zeno behavior is strictly excluded. Finally, the effectiveness of the proposed fully distributed ETC protocol is illustrated by a numerical example.

Cooperative Fault-Tolerant Output Regulation for Multiagent Systems by Distributed Learning Control Approach.

In this article, a new distributed learning control approach is proposed to address the cooperative fault-tolerant output regulation problem for linear multiagent systems with actuator faults. First, a distributed estimation algorithm with an online learning mechanism is presented to identify the system matrix of the exosystem and to estimate the state of the exosystem. In particular, an auxiliary variable is introduced in the distributed estimation algorithm to construct a data matrix, which is used to learn the system matrix of the exosystem for each subsystem. In addition, by resetting the state of the estimator and by using the identified matrix to update the estimator, all subsystems can reconstruct the state of the exosystem at an initial period of time, which is used for the neighbor subsystem to learn the system matrix of the exosystem. Based on the designed estimator, a novel distributed fault-tolerant controller is developed. Compared with the existing cooperative output regulation results, the system matrix of the exosystem considered in this article is unknown for all subsystems. Finally, a simulation example is provided to show the effectiveness of the obtained new design techniques.

Adaptive Observer-Based Output Regulation of Multiagent Systems With Communication Constraints.

In the absence of assuming that all agents know the system matrix of the external system, for heterogeneous linear multiagent systems (MASs), this article resolves the cooperative regulation problem in the presence of communication constraints. Based on the mild assumption on the digraph, two novel adaptive protocols are presented to solve the cooperative output regulation problem (ORP) via state feedback and measurement output feedback subject to snatchy and asynchronous information exchange between agents, unknown time-varying delays, and probable information losses. Finally, some simulations are offered to demonstrate the validity of our results about the problem.

Distributed Event-Triggered Control for Cooperative Output Regulation of Multiagent Systems With an Online Estimation Algorithm.

In this article, the cooperative output regulation problem of heterogeneous multiagent systems has been investigated. It is assumed that only a few agents could know the system matrix of the exosystem and no agent knows the topological information. Under these conditions, a novel distributed online algorithm is proposed to estimate the information relevant to the topology. Based on this algorithm, a distributed event-triggered adaptive observer is designed such that each agent can observe the exosystem. It is theoretically shown that the proposed distributed controller will make the multiagent system achieve cooperative output regulation asymptotically. Finally, a simulation is presented to show the effectiveness of the result.

Event-based cooperative global practical output regulation of multi-agent systems with nonlinear leader

This paper presents a distributed event-based high gain feedback design for the cooperative global practical output regulation problem of nonlinear multi-agent systems with unit relative degree subject to the general nonlinear leader system. We first convert global practical output regulation problem into global practical stabilization problem, then prove the input-to-state stability of the closed-loop system by regarding the sampling error and the steady-state of the actuator together as the external input. Based on the high gain feedback technique, the input-to-state gain function can be made sufficiently small, and hence the tracking error can converge to an arbitrary predefined small residual set around the origin. A distinguishing feature of our result is that, our controller is static and purely digital, thus, giving rise to quite a simple structure.

Robust cooperative output regulation of multi-agent systems via adaptive event-triggered control

This paper investigates the robust cooperative output regulation problem of uncertain linear multi-agent systems with additive disturbances via the celebrated internal model principle. Two novel distributed controllers are designed based on the adaptive control strategy and the event-triggered transmission scheme, where the adaptive control strategy is utilized to avoid the requirement for a priori knowledge of the minimal nonzero eigenvalue of the Laplacian matrix associated with the communication topology, and the event-triggered transmission scheme is utilized to reduce the frequency of data transmission. It is shown that the proposed control schemes achieve robust cooperative output regulation asymptotically and Zeno behavior is excluded. Finally, a simulation example is presented to illustrate the effectiveness of the proposed controllers.

Cooperative Output Regulation for Multi-Agent Systems with EDMD Leader Approximation

This paper presents a distributed output regulation algorithm for the leader-follower heterogeneous multi-agent system with unknown leader dynamics. The unknown nonlinear dynamics of the leader agent are reconstructed based on a data-driven transformation that lifts the nonlinear dynamics to a linear space that approximates it. An adaptive distributed observer algorithm is designed to estimate the leader states and its linear model approximation for each follower agent, since it is considered that the leader communicates only to a subset of followers. To design the output synchronization protocol, a local state feedback control is developed for each agent. The proposed algorithm is validated through simulation studies.

Robust leader-following output regulation of uncertain multi-agent systems with time-varying delay

In this paper, the robust analysis and design of leader-following output regulation for multi-agent systems described by general linear models is given in presence of time-varying delay and model uncertainty. To this aim, a new regulation protocol for the closed-loop multi-agent system under a directed graph is proposed. An important specification of the proposed protocol is to guarantee the leader-following output regulation for uncertain multi-agent systems with both stable and unstable agents. Since many signals can be approximated by a combination of the stationary and ramp signals, the presented results work for adequate variety of the leaders. The analysis and design conditions are presented in terms of certain matrix inequalities. The method proposed can be used for both stationary and ramp leaders. Simulation results are presented to show the effectiveness of the proposed method.

Cooperative output regulation of multi-agent systems with switched leader dynamics

ABSTRACTIn this paper, the cooperative output regulation problem for heterogeneous multi-agent systems is addressed by considering a switched leader dynamics. The switched leader dynamics consists of multiple linear models and a switching rule governing the switches among them. A switched leader is capable of generating various sophisticated reference signals for more complicated multi-agent coordination tasks. A novel distributed hybrid impulsive switching control scheme is proposed to achieve cooperative output regulation. Distributed switching stability is established using the average dwell-time technique with multiple Lyapunov functions. Moreover, the associated distributed control synthesis conditions are formulated in terms of linear matrix inequalities plus linear matrix equations. As a result, both switching rules for the leader and distributed switching protocols for the followers can be jointly synthesised via efficient semi-definite programming. An example has been used to demonstrate the effectiveness of the proposed approach.

Cooperative global robust group output regulation for multi-agent systems with heterogeneous uncertain second-order nonlinear dynamics

In this paper, we study the global robust group output regulation problem for multi-agent systems with heterogeneous uncertain second-order nonlinear dynamics. The intelligence factor is introduced to construct a designed graph matrix which overcomes the communication influence between multiple coupled subnetworks with different exosystems. In terms of internal model principle, the global robust group output regulation problem is converted into the global robust dynamic stability problem of the so-called augmented multi-agent system. Further, the augmented multi-agent system is globally stabilized via a distributed state feedback control law. A special case of the main result of this paper leads to the solution of the global robust multi-tracking control problem for nonlinear multi-agent networks. A simulation is performed to illustrate the effectiveness of the theoretical results.

Quantized distributed output regulation of multi-agent systems

Quantized distributed output regulation of multi-agent systems

Distributed event-triggered output regulation of multi-agent systems

Motivated by the future use of embedded microprocessors with limited resources and limited computational resources, the distributed output regulation with event-driven strategies problem of linear multi-agent systems is considered in this paper. The main task is to design distributed feedback by employing event-triggered technique for multi-agent systems such that all agents can track an active leader, and/or distributed disturbance rejection. Both leader and disturbance are generated by some external system (exosystem). Both distributed static and dynamic feedback with event-triggered strategy are constructed here. Then, the input-to-state stability of the closed-loop multi-agent system is analysed. Finally, a numerical example is given to validate the proposed control.

Cooperative output regulation of multi-agent systems coupled by dynamic edges

This paper investigates a new class of linear multi-agent systems, in which nodes are coupled by dynamic edges in the sense that each edge has a dynamic system attached. The outputs of the edge dynamic systems combine to form the external input of the node dynamic system, which is called neighboring input; while the outputs of the node dynamic systems are inputs of the edge dynamic systems that therefore can not be directly controlled. Distributed controllers for nodes are presented to realize output synchronization and output cooperation. Output cooperation makes the outputs of nodes realize some cooperation that here is specified as making the neighboring input track a predefined trajectory. The controllers depending on local state and neighboring inputs are designed by combining the feedback passivity theory and the internal model principle. A simulation example on the cooperated current control of an electrical network illustrates the potential applications of the analytic results.