This work studies the problem of data-driven event-triggered control of continuous-time multiagent systems (MASs) with communication delays. A hybrid system approach is proposed to address this problem, hybrid dynamic event-triggering mechanism (DETM) is utilized to ensure strong Zeno-freeness and estimated system matrix is introduced to design time-varying state estimator. By using several auxiliary variables, the closed-loop MAS is described into hybrid system form, that can completely describe the flow dynamics and jump dynamics of the MAS in the presence of communication delays. Then, data-based controller gain matrix design is developed and an estimator is designed to estimate unknown system matrix. After that, based on derived model-based stability conditions and combined with data-driven representation of MAS, data-based stability analysis and event-triggering mechanism (ETM) design results are obtained. The main advantages of the proposed approach in contrast with existing works are that accurate system model is not needed and strong Zeno-freeness is ensured under the scenario with communication delays. Finally, the effectiveness of the proposed method is verified by simulation example.

This paper addresses the problem of prescribed-time optimal formation control for nonlinear multi-agent systems (MAS) via reinforcement learning (RL). First, a new finite horizon performance cost function is constructed, which incorporates specified time and terminal constraints, thereby it is useful for embedding the prescribed convergence time performance into optimal control framework. Based on the cost function, RL-based optimal formation controller is subsequently devised under actor-critic structure, by incorporating terminal constraint errors into the critic update law, it ensures that the optimal value function can be approximated while satisfying terminal constraints. Then, the prescribed-time optimal formation controller is designed by integrating an adjustment function with the devised optimal formation controller, with which, the formation tracking errors are ensured to converge to the origin within specified time. The proposed approach provides some advantages such as system model information is not required, optimal performance is achieved with satisfied terminal constraints, and asymptotic rather than bounded prescribed-time formation control is achieved. Finally, the effectiveness of the proposed strategy is validated through simulation examples.

This paper investigates the consensus problem of multi-agent systems (MAS) subject to denial-of-service (DoS) attacks and actuator faults. For the aim of decreasing the communication frequency among agents, we first design a novel double-layer event-triggering mechanism (DLETM) with inherently joint characteristic1, the first layer ETM only works inside an agent and serves second layer ETM, and network information transmission is activated by the second layer ETM. In addition, resilient triggering conditions related to DoS attack status are constructed. Then, an iterative observer is developed to estimate the actuator faults, it is formally shown that the estimation errors converge as iteration number increases. For consensus analysis and DLETM design, a novel Lyapunov function with inverse trigonometric function is constructed to overcome the limitation of existing Lyapunov function, based on which, sufficient stability conditions are provided for the MAS under DoS attacks and faults. Finally, we verify the performance of the proposed approach using a simulation example.

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.

This paper develops a novel hybrid system approach to address the event-triggered stabilization problem of largescale T-S fuzzy systems subject to variable long transmission delays. Various changing behaviours of deviation errors caused by transmission delays, as well as the changes of some auxiliary variables are modeled by a hybrid dynamical system with flow dynamics and jump dynamics. Then, under the hybrid control framework, an observer based anti-disturbance controller and a delay-independent hybrid event-triggering mechanism (HETM) are proposed to stabilize the closed-loop system, while guaranteeing desired performance in disturbance attenuation and delay tolerance. Compared with the case that small transmission delays could naturally lead to delay-independent HETM, the long transmission delays pose many difficulties. Given this, we propose a more robust triggering condition with only using several memorized previous states to guarantee the HETM to be delay-independent even in case with long transmission delays. Moreover, the obtained stability conditions avoid involving lower and upper bounds of transmission delays in matrix inequalities, thus can be delay-independent and significantly simplified. Relationships between system stability and maximally allowable transmission delay are transformed to designing proper auxiliary functions offline. Finally, the effectiveness of proposed control protocol is demonstrated by a numerical example.

This work studies event-triggered bipartite consensus problem of multi-agent systems (MAS) with structurally balanced signed graph. A hybrid system approach is proposed to deal with the leaderless and leader-following bipartite consensus problems in a unified framework, and a novel hybrid event-triggering mechanism (ETM) is proposed to reduce the usage of communication resources. By appropriately defining closed-loop states, a unified hybrid model is constructed for both leaderless and leader-following MAS. Then, stability analysis and ETM design results are given under hybrid systems framework. It is worth noting that the designed hybrid ETM is in decentralized form rather than distributed form. Moreover, the lower bound of triggering intervals can be pre-selected, i.e., Zeno-freeness is guaranteed, that is important for control implementation. The proposed method is applied to satellite formation system in simulation results to show the effectiveness.Note to Practitioners—This paper considers bipartite consensus control problem of MAS, which can be applied to some practical systems, e.g., bidirectional formation of unmanned air vehicles, since the control objective in these applications can be transformed into bipartite consensus control problem of MAS. Compared with the existing results, a hybrid system approach is proposed for consensus analysis of MAS with or without leader, and a novel event-triggering mechanism is proposed, which is more easier to be implemented, so, the proposed approach is more friendly for control engineers. The obtained results are applied to satellite formation control problem and the effectiveness is verified, and it is expected that the proposed approach can be extended to MAS with more realistic network-induced constraints and applied to more practical engineering systems.

This article investigates the secondary control problem of islanded microgrid under hybrid systems framework. Owing to network-induced imperfections caused by communication and limited communication resources, we consider the event-triggered secondary control problem under time-varying delays. A hybrid dynamic event-triggering mechanism (ETM) (DETM) is proposed to reduce the usage of communication resources, the event triggering interval is enforced to be lower bounded by strictly positive value. A hybrid closed-loop model is constructed that incorporates the communication delays and ETM, and it facilitates stability and performance analysis. Lyapunov-based stability conditions are proposed, while the maximum allowable delay can be determined. Moreover, the proposed hybrid DETM ensures that the minimum event-triggering interval can be designable and prespecified, even in the presence of disturbances, which is important for control implementation. Finally, the effectiveness of the proposed control strategy is illustrated by simulation examples.

This article proposes a hybrid systems approach to address the sampled-data leaderless and leader-following bipartite consensus problems of multiagent systems (MAS) with communication delays. First, distributed asynchronous sampled-data bipartite consensus protocols are proposed based on estimators. Then, by introducing appropriate intermediate variables and internal auxiliary variables, a unified hybrid model, consisting of flow dynamics and jump dynamics, is constructed to describe the closed-loop dynamics of both leaderless and leader-following MAS. Based on this model, the leaderless and leader-following bipartite consensus is equivalent to stability of a hybrid system, and Lyapunov-based stability results are then developed under hybrid systems framework. With the proposed method, explicit upper bounds of sampling periods and communication delays can be calculated. Finally, simulation examples are given to show the effectiveness.

This article studies the self-triggered consensus control problem for linear multiagent systems (MASs) with the aim of improving resources utilization efficiency, e.g., saving communication bandwidth and reducing node energy consumption. First, a distributed control protocol is designed and a novel decentralized dynamic self-triggering mechanism (DDSTM) is proposed, with which, each agent can not only compute its own next triggering instant but also is able to compute the neighbors’ next triggering instant. Then, a hybrid system model is constructed to completely describe the close-loop system with jump dynamics. Based on the hybrid model, Lyapunov conditions are derived for MAS consensus analysis. The proposed DDSTM can overcome some limitations of the existing distributed STMs in the sense of synchronously acquiring consensus error or uniquely determining triggering instants, moreover, it allows transceivers to be turned on only at triggering instants and enter into sleep mode at the rest time, such that node energy is efficiently saved. Preadjustable minimum triggering interval is imposed between any consecutive triggering events; thus, a minimum sleep period for transceivers is always guaranteed. Finally, a numerical example is presented to demonstrate the effectiveness of the proposed approach.

This article addresses the event-triggered consensus problem of multiagent systems (MASs) with packet losses. The packet losses are not restricted to be identical, and a hybrid systems framework is proposed to handle the considered problem with or without leader in a unified framework. Distributed control law is constructed based on an estimator, whose dynamics are related to whether packet losses occur. A novel hybrid event-triggering mechanism (ETM) is proposed, and a lower bound of the interevent times is enforced to guarantee Zeno-freeness. For stability analysis, a unified hybrid model is constructed to describe the dynamics of MAS with or without leader. In accordance to this model, how to design the hybrid ETM and consensus analysis are formally developed, and the maximum allowable successive packet losses can be explicitly computed. Moreover, even if there exist nonlinearities and disturbances in system dynamics, and the leader has nonzero input, the proposed method can still be applied. Finally, examples are provided to illustrate the superiority of the proposed method.

This article develops a novel hybrid switching control (HSC) approach to the consensus of multiagent systems (MASs), and the objective is to further improve the transient consensus performance compared with a reset control approach in recent results. First, a hybrid switched controller is introduced, which consists of two working modes: 1) reset control mode and 2) gain mode. Through appropriate switching mechanism design, the controller output signal can be guaranteed to be continuous, and the input-output of the switched controller always has the same sign. Then, HSC is applied to the consensus of MAS, and a consensus protocol consisting of proportional control part and HSC part is proposed. By introducing binary-value variables, an appropriate closed-loop model is constructed, and the Lyapunov-based consensus analysis results are obtained. Finally, an example is provided to show the superiority of the proposed approach.

In this article, we investigate the observer-based event-triggered consensus problem of multiagent systems with disturbances. A reset observer consisting of a linear observer and reset element is proposed, the reset element endows the reset observer the ability to improve transient estimation performance compared with traditional linear observers. A hybrid dynamic event-triggering mechanism (ETM) is proposed, in which an internal timer variable is introduced to enforce a lower bound for the triggering intervals such that Zeno-free triggering can be guaranteed even in the presence of disturbances. Then, in order to describe the closed-loop system with both flow dynamics and jump dynamics, a hybrid model is constructed, based on which the Lyapunov-based consensus analysis and dynamic ETM design results are presented. In contrast with linear observer-based consensus protocols and the existing dynamic ETMs, the system performance can be improved and continuous communication between neighboring agents is not needed. Finally, a simulation example is provided to show the effectiveness of the proposed methods.

In the existing literature, reset control has been shown to have great potential to improve transient performance of linear systems, but reset-induced jump dynamics bring difficulties for stability analysis, especially under the network environment. In this article, we apply reset control to the consensus of multiagent systems (MASs) with event-triggered communication, and a novel reset mechanism (RM) and a hybrid event-triggering mechanism (ETM) are proposed with guaranteed Zeno-freeness. The state space is decomposed into multiple flow sets and jump sets according to the RM and ETM, and a hybrid model of the MASs is constructed such that the reset induced and event-trigger induced jump dynamics can be handled in a unified framework. Based on the hybrid model, a novel hybrid systems framework is presented for consensus analysis and co-design of RM and ETM. Finally, the proposed design is verified with a simulation example.

This article investigates the dynamic event-triggeredH∞control problem for nonlinear networked control systems with unreliable communication channel, variable communication delays, and limited bandwidth. The nonlinear plant is represented by discrete-time polynomial fuzzy model. First, a decentralized dynamic event-triggered mechanism is proposed to determine whether the measured data are transmitted or not, and in order to exclude data collision caused by limited bandwidth, novel try-once-discard and flexible round-robin scheduling protocols are proposed to assign communication channel to certain sensor node. Then, Bernoulli distribution is employed to model the unreliable communication channel, and a new random sequence is developed to model the received data sequence under the effect of data losses and scheduling protocols. Furthermore, a discrete-time stochastic system model with both state and error delays is constructed, and sufficient conditions in the form of sum-of-squares are developed for the design ofH∞controllers such that the closed-loop system is stochastically stable and preserves guaranteedH∞performance. Finally, two simulation examples are provided to illustrate the effectiveness of the proposed results.

This article investigates the consensus problem of multiagent systems (MASs) with the reset control approach. Reset control has been shown to possess great potential to improve transient system performance, but reset-induced state jump dynamics bring difficulties for consensus analysis, especially under the network environment. In this article, a novel reset element is developed, and time regularization is utilized to exclude Zeno behavior. The case with continuous communication is first considered, a distributed proportional integral + reset consensus protocol is proposed, which consists of the proportional-integral controller and the reset mechanism. The results are further generalized to the case with asynchronous sampling, which relaxes the requirement for continuous communication and clock synchronization. A hybrid model of the MAS is constructed to describe the system dynamics, and a hybrid systems approach is proposed to handle the reset- and sampling-induced jump dynamics in a unified framework. Moreover, a novel Lyapunov function is proposed and LMI-based stability conditions are given. Finally, an example is provided to show the effectiveness of the proposed methods.

This paper investigates the leader-following consensus problem for multiagent systems (MASs) with communication delays. A novel hybrid event-triggered control scheme is developed and a hybrid system approach is proposed to design the event-triggering condition. Meanwhile, by means of temporal regularization, a strictly positive lower bound on the interevent times can be guaranteed, that is, Zeno-freeness can be guaranteed. The MASs are first described as a closed-loop system with both flow dynamics and jump dynamics, where the jump dynamics is induced from the triggering events and communication delays. Then, a hybrid model of the MASs is constructed under a hybrid systems framework. Based on this hybrid model, how to construct the Lyapunov function is given and the event-triggering condition design is also developed, such that the asymptotic consensus is achieved. Finally, an example is provided to show the effectiveness of the proposed approach.

Reset control has been shown to have advantages over linear time-invariant controllers, especially, for control loops with time-delays. In this paper, in order to adapt reset control to networked control systems (NCS), multi-input multi-output discrete-time reset control model is first established by decomposing the controller output and defining appropriate flow set and jump sets. Then, we apply discrete-time reset controllers to NCS with time-varying delays in both forward and feedback channels, the modeling framework of networked reset control systems is given based on switched linear parameter-varying systems, and stability conditions are derived in terms of linear matrix inequalities. Finally, experimental and simulation examples are presented to illustrate the superior performance of the proposed approaches.