Event-triggered Leader-following Consensus Research Articles

Hybrid dynamic event-triggered leader-following consensus for multi-agent systems with external disturbances

Herein, we address the leader-following consensus for multi-agent systems with a directed graph while considering external disturbances. To optimize resource utilization, we propose a hybrid dynamic event-triggered mechanism (HDETM) that minimizes the inter-agent communication and reduces the frequency of controller updates. Furthermore, regularization techniques are employed to ensure that the considered system maintains a Zeno-free behavior even in the presence of an external disturbance by guaranteeing a strictly positive inter-event time. Additionally, we propose a hybrid system framework incorporating auxiliary variables to depict both flow and jump dynamics. A Lyapunov consensus analysis is performed within this framework to verify finite-gain L2 stability. Finally, we validate the efficacy of the HDETM design method through numerical simulations.

Event-Triggered Leader-Following Consensus Control of Nonlinear Multiagent Systems With Generally Uncertain Markovian Switching Topologies

Event-Triggered Leader-Following Consensus Control of Nonlinear Multiagent Systems With Generally Uncertain Markovian Switching Topologies

Distributed Dynamic Event-Triggered Leader-Following Consensus for Nonlinear Multiagent Systems Over Fading Channel.

This article investigates the leader-following consensus problem of discrete-time nonlinear multiagent systems (MASs) over fading channels. With the consideration of the transmission among followers maybe affected by the fading networks, the nonidentical fading channels model is constructed. To reduce the transmission network burden, the dynamical event-triggered mechanism (DETM) is developed. Different from most of existing event-triggered strategies, the threshold parameter in the developed dynamical event-triggering condition is dynamically adjusted according to a dynamic rule. Based on the DETM, a distributed consensus control protocol is designed under fading channels. Then, sufficient criteria are provided to ensure that MASs can achieve the leaser-following consensus, and satisfy the H∞ performance index in the presence of fading channels. The desired controller parameters can be derived in terms of solutions of matrix inequalities that are lightly solvable. In the end, simulation results show that the designed dynamical event transmission policy is capable of diminishing communication burden more promptly and effectively than some existing ones.

Event-Triggered Distributed Consensus Tracking for Nonlinear Multi-Agent Systems: A Minimal Approximation Approach

In this paper, a minimal-approximation-based event-triggered leader-following consensus control scheme is proposed for nonlinear multi-agent systems with unknown actuator dead-zone. To save communication resources, a distributed consensus controller based on the event-sampled states is designed for each follower, which reduces the number of transmissions in the sensor-to-controller and controller-to-actuator channels. Considering that a large number of function approximators are employed in the existing distributed event-triggered schemes of uncertain nonlinear multi-agent systems, thereby consuming massive computational resources. The minimal approximation technology, i.e., designing un-requirement-calculated virtual control laws and employing one function approximator in each local controller, is introduced in our proposed scheme. Meanwhile, the proposed minimal-approximation-based event-triggering mechanism only needs to monitor one triggering condition for each follower, which further reduces the computational burden. Finally, the stability of the closed-loop system is strictly proven by using the Lyapunov extension theorem, and two examples are given to demonstrate the effectiveness of the proposed algorithm.

Topology-based dynamic event-triggered leader-following consensus of multi-agent systems under switching topologies

This paper is devoted to the topology-based dynamic event-triggered leader-following consensus issue of general linear multi-agent systems under switching topological structures. The novel topology-based distributed dynamic event-triggered rule is formed, in which a topology-based dynamic auxiliary variable is introduced to reduce the conservatism and save resources. Under novel triggering rules, topology-based distributed event-triggered controllers are constructed. Different control gains are designed for different topological structures. Compared with existing works, conservatism is further reduced. Then the leader-following consensus is achieved with a global exponential convergence rate. Moreover, the average dwell time method is adopted to relax restrictions on the switching speed of topological structures and an original analytical thought is put forward to rule out the Zeno phenomenon concisely and clearly. Finally, two numerical examples and a realistic mass–spring system are utilized to verify the feasibility and superiority of the proposed theory.

Double event-triggered leader-following consensus and fault detection for Lipschitz nonlinear multi-agent systems via periodic sampling strategy

Double event-triggered leader-following consensus and fault detection for Lipschitz nonlinear multi-agent systems via periodic sampling strategy

Observer-based event-triggered leader-following consensus of multi-agents with generalized Lipschitz nonlinear dynamics

This paper discusses a leader-following consensus problem for nonlinear multi-agent systems (MASs) subjected to generalized Lipschitz-type nonlinearity using output feedback. An event-triggered (ET) leader-following control scheme, based upon estimated states using observers, is proposed for efficient bandwidth utilization by application of invariant sets. Distributed observers are designed to estimate the states of the followers because actual states are not always readily available. Besides, in order to reduce unnecessary data communication among the followers, an ET strategy has been formulated which excludes Zeno behavior as well. Under this proposed scheme, sufficient conditions are formulated using Lyapunov theory. These conditions not only guarantee the asymptotic stability of estimation error, but also ensure the tracking consensus of nonlinear MASs. Further, a simple and less conservative design approach using a decoupling scheme for assuring necessity and sufficiency for the main design approach has also been explored. The decoupling scheme is similar to separation principle for linear systems. Contrary to the existing works, the nonlinear systems considered in this study cover a wide family of Lipschitz nonlinearities, including both globally and locally Lipschitz systems. Moreover, the proposed approach is more efficient in handling ET consensus. Finally, the obtained results are verified with single link robots and modified Chua’s circuits.

Event-triggered leader-following consensus of multi-agent systems under semi-Markov switching topology with partially unknown rates

An event-triggered leader-following consensus problem for multi-agent systems with nonlinear dynamics was investigated in this study. The interaction topologies among the agents that we considered are randomly switched ones, governed by a semi-Markov process with partially unknown rates. By building the state error model between the leader and followers, the consensus problem is first converted into a stability problem. Moreover, an event-triggered transmission scheme based on sampling data was proposed to reduce communication redundancy. The consensus controller and event-triggered parameters can be designed effectively. By constructing a Lyapunov–Krasovskii functional (LKF) with a triple integral, the sufficient conditions required to guarantee the event-triggered consensus can be reached with respect to the linear matrix inequalities (LMIs). Ultimately, the validity of the theoretical results is demonstrated by a numerical example.

Memory-based event-triggered leader-following consensus for T-S fuzzy multi-agent systems subject to deception attacks

In this paper, the problem of fuzzy model-based leader-following consensus control for multi-agent systems (MASs) under deception attacks is investigated. For the sake of alleviating the communication burden, a novel memory-based event-triggered scheme (METS) is first proposed for the considered MASs to reduce redundant data transmission, and the leader-following consensus can be achieved faster with a smaller adjustment error by applying the historical released packets. Considering the designed METS and upper-bounded attacks synthetically, the closed-loop fuzzy system model is well established. Furthermore, with the help of Lyapunov-Krasovskii technique, some sufficient conditions are derived to ensure the consensus of MASs subject to deception attacks. Finally, a simulation example is introduced to manifest the effectiveness of the proposed method.

Fixed-time leader-following/containment consensus of nonlinear multi-agent systems based on event-triggered mechanism

This study focuses on the fixed-time event-triggered leader-following consensus issue for nonlinear multi-agent system with uncertain disturbances. First, two distributed fixed-time controllers based on event-triggered mechanism are put forward to address this issue. Different from the existing finite-time control techniques, the proposed controller can guarantee that the settling time does not depend on the initial conditions and the continuous controller updates cannot be required. Moreover, compared with the existing fixed-time control methods, the fixed-time event-triggered tracking problem for multi-dimensional nonlinear multi-agent system with uncertain disturbances is considered for the first time in this paper. To avoid continuous communication among agents, a novel triggering mechanism is further proposed. Furthermore, the fixed-time event-triggered containment consensus with multiple leaders is considered. No agent exhibits the Zeno behavior in these two consensus issues. The effectiveness of main theoretical findings is demonstrated by two illustrative examples finally.

Leader-following consensus control for semi-Markov jump multi-agent systems: An adaptive event-triggered scheme

The problem of event-triggered leader-following consensus control for semi-Markov multi-agent systems is investigated in this paper. A semi-Markov process is used to describe the sudden parameter changes between every agent. An adaptive event-triggered control strategy is proposed to make a balance between reducing unnecessary communication and meeting the required performance. A control protocol which can resist actuator faults is used to ensure the reliable leader-following consensus. By employing the Lyapunov–Krasovskii functional method, some sufficient conditions are provided to guarantee that the leader-following consensus can be achieved in mean-square sense. The consensus controller and the event-triggered parameter can be co-designed. Finally, the effectiveness of the proposed method is verified by a F-404 aircraft engine system.

Event-triggered leader-following consensus of multiple mechanical systems with switched dynamics

This paper investigates the event-triggered leader-following consensus problem for a class of multiple mechanical systems with switched dynamics. Based on the graph theory, Lyapunov stability theory, backstepping technique and event-triggered control theory, an event-triggered protocol is proposed for the considered multiple mechanical systems. It is proved that the practical leader-following consensus can be achieved by the proposed protocol. Meanwhile, to exclude the Zeno behaviour, a positive lower bound of inter-event intervals is given. Finally, we provide a numerical simulation to illustrate the effectiveness of the given protocol.

Event‐triggered leader‐following consensus for multi‐agent systems with external disturbances under fixed and switching topologies

In this study, the event-triggered leader-following consensus problem for multi-agent systems with external disturbances is addressed under fixed and switching topologies. First, based on an extended state observer, a novel distributed event-triggered protocol is designed under a fixed topology to achieve consensus disturbance rejection and eliminate Zeno behaviour. Second, for the case of switching topologies which do not always have a directed spanning tree, an observer-based event-triggered protocol is proposed with topology-dependent average dwell time. Moreover, both protocols presented are without the requirement of continuous information transmission among neighbouring agents. Finally, two numerical examples are provided to illustrate the effectiveness of the results.

Event-Based Consensus for General Linear Multiagent Systems under Switching Topologies

In this paper, event-triggered leader-following consensus of general linear multiagent systems under both fixed topology and switching topologies is studied. First, centralised and decentralised event-triggered control strategies based on neighbors’ state estimation are proposed under fixed topology, in which the controller is only updated at the time of triggering. Obviously, compared with the continuous time control algorithms, the event-triggered control strategies can reduce the communication frequency among agents effectively. Meanwhile, event-triggering conditions are derived for systems to achieve consensus by using the Lyapunov stability theory and model transformation method. Then, the theoretical results obtained under the fixed topology are extended to the switching topologies, and the sufficient conditions for the system to achieve leader-following consensus under the switching topologies are given. However, different from fixed topology, the control input of each agent is updated both at event-triggering and topology switching time. Finally, Zeno behaviors can be excluded by proving that the minimum triggering interval of each agent is strictly positive, and the effectiveness of the event-triggered protocol is verified by simulation experiments.

Event-Triggered Leader-Following Consensus for Nonlinear Multiagent Systems Subject to Actuator Saturation Using Dynamic Output Feedback Method

This paper addresses the distributed event-triggered consensus problem for a class of nonlinear multiagent systems subject to actuator saturation. A new distributed event-based dynamic output feedback controller is put forward via the relative output measurements of neighboring agents. It removes the impractical assumptions that the controllers for agents have to update continuously and the observers embedded in agents have to share information with their neighbors, thus the energy consumptions of agents are significantly reduced. Two event-triggered strategies for the cases with and without continuous communication among neighboring agents are established. Sufficient conditions are derived in terms of matrix inequalities to guarantee the exponential leader-following consensus. The problem of designing a distributed event-triggered control law such that the domain of attraction for consensus errors is enlarged, formulated, and solved as an optimization problem with matrix inequality constraints. Simulation results are given to verify the effectiveness of the theoretical results.

Dynamic event-triggered leader-following consensus control of a class of linear multi-agent systems

We address the leader-following tracking consensus issue for a class of linear multi-agent systems (MASs) via dynamic event-triggered (DET) approaches in this paper. The DET communication mechanism is introduced by an additional internal dynamic variable, and is developed to schedule agents’ data transmission. State observers are also employed to tackle the scenario wherein inner information of follower agents are not available for measurement. And then, state-based and observer-based distributed control proposals are proposed on the basis of dynamic event-triggered mechanism (DETM), respectively. To avoid continuous measurement information monitor, we present a technical approach for generation of the combinational information from their own neighboring agents only at event instants. The stabilities of the resulting closed-loop systems, both state-feedback one and output-feedback one, are rigorously analyzed in theory, and it is proven that all signals in the closed-loop system are bounded and Zeno behavior is also excluded. Simulation examples are presented to illustrate the theoretical claims.

Event-triggered leader-following consensus for multi-agent systems with semi-Markov switching topologies

This paper investigates the event-triggered leader-following consensus problem for a multi-agent system with semi-Markov switching topologies. A sampled-data-based event-triggered transmission scheme is introduced to reduce unnecessary communication. By modeling the switching of network topologies by a semi-Markov process and adopting an event-triggered transmission scheme, a new consensus protocol is proposed. Compared with the traditional Markovian switching topologies, the transition rates in the semi-Markov switching topologies are time-varying, which is more general and practicable. Through utilization of an appropriate Lyapunov–Krasovskii functional, some sufficient conditions are derived, which guarantee that the leader-following consensus can be achieved in mean-square sense. Moreover, the consensus gain matrices and parameter of the event-triggered scheme can be efficiently solved out. Finally, a numerical example illustrates the effectiveness of the proposed design technique.

Leader-following consensus in second-order multi-agent systems with input time delay: An event-triggered sampling approach

This paper analytically investigates an event-triggered leader-following consensus in second-order multi-agent systems with time delay in the control input. Each agent׳s update of control input is driven by properly defined event, which depends on the measurement error, the states of its neighboring agents at their individual time instants, and an exponential decay function. Necessary and sufficient conditions are presented to ensure a leader-following consensus. Moreover, the control is updated only when the event-triggered condition is satisfied, which significantly decreases the number of communication among nodes, avoided effectively the continuous communication of the information channel among agents and excluded the Zeno-behavior of triggering time sequences. A numerical simulation example is given to illustrate the theoretical results.