Class Of Heterogeneous Multi-agent Systems Research Articles

Adaptive fault-tolerant control for a class of nonlinear multi-agent systems with multiple unknown time-varying control directions

In this paper, we investigate the consensus tracking control for a class of heterogeneous multi-agent systems with multiple unknown time-varying control directions and unknown direction actuator faults. Different from existing work, the directions of the multiple time-varying control coefficients are subject to fault-induced sign-switching. To address this challenge, a series of high-order Lyapunov functions and differentiable functions are introduced to avoid non-integrable terms. Then, a novel contradiction statement and some Nussbaum functions are used to handle the summation of multiple unknown control coefficients with time-varying amplitudes and directions. Meanwhile, a novel distributed observer with quantized communication is introduced to track a reference trajectory with unknown dynamics. It is shown that all closed-loop signals are globally uniformly bounded and the tracking errors converge to residual sets that can be made arbitrarily small. Simulation results illustrate the effectiveness of the proposed scheme.

Dual-Stage Heterogeneous Multiagent Systems Surrounding Control for a Motional Target

This paper addresses the dynamic target surrounding control problem for a class of heterogeneous multi-agent systems (MASs). To surround a motional target with a time-varying velocity, a distributed observer is established by employing perturbation system analysis, which can simultaneously retrieve both target state and dynamics. Then a distributed dual-stage cooperative control scheme based on output regulation principle is proposed to fulfill the evenly surrounding control mission, i.e., all the heterogeneous agents moving along a common circle around the dynamic target with an identical desired radius and evenly distributed phases. Afterwards, an optimal selection protocol of switching instant between the collective chasing and surrounding stages is provided as well. Significantly, sufficient conditions are derived to guarantee the asymptotical stability of such closed-loop heterogeneous MASs. Finally, numerical simulations are conducted to verify the effectiveness of the proposed surrounding control scheme.

Adaptive Autonomous Synchronization of a Class of Heterogeneous Multi-Agent Systems

Adaptive Autonomous Synchronization of a Class of Heterogeneous Multi-Agent Systems

Estimator-based event-triggered output synchronization for heterogeneous multi-agent systems under denial-of-service attacks and actuator faults

This paper studies the output synchronization problem with an event-triggered communication scheme for a class of heterogeneous multi-agent systems under denial-of-service (DoS) attacks and actuator faults. DoS attacks may render the followers incapable of acquiring the leader's states and actuator faults may cause the actuators to not perform the control operation well. Comparing with the previous studies adopting the continuous communication mechanism, a novel switching estimator with an event-triggered communication strategy is designed to estimate the leader's states for each follower. By using the Lyapunov stability theory and the average dwell time method, sufficient conditions for the upper bound of the frequency of DoS attacks are derived. The estimation error system is proved to be exponentially stable. Besides, in order to compensate for actuator faults, a distributed adaptive fault-tolerant controller is proposed. The conditions for the stability of the output regulation error when the systems suffer from DoS attacks and actuator faults are given. A simulation example is proposed to prove the effectiveness of the main results.

Distributed hybrid control for heterogeneous multi-agent systems subject to deception attacks and its application to secondary control for DC microgrid

This paper addresses the mean-square quasi-consensus problem for a class of heterogeneous multi-agent systems (MASs) with cascade-type two-layer structure subject to discrete-time deception attacks. A two-layer distributed hybrid controller is proposed based on the structural characteristics of the considered MASs. The deception attacks are supposed to occur in the upper-layer communication channel and their occurrences are modeled by a Bernoulli process. The discrete-time deception signal is considered as a bounded external disturbance sequence, so the mean-square quasi-consensus problem can be reduced to a mean-square exponential input-to-state stability (MSEISS) problem. A novel MSEISS analysis method combined with the use of a weighted discontinuous Lyapunov function is developed to establish a MSEISS criterion of the consensus error system, where the robustness performance of the mean-square quasi-consensus with respect to the randomly occurring deception attacks is quantified by the MSEISS gain. The effectiveness of the proposed resilient distributed hybrid control algorithm is verified through numerical simulations. Specifically, the proposed resilient control algorithm is applied to the secondary control of DC microgrid with discrete interaction. Several case studies show that the resulting resilient distributed hybrid secondary control algorithm has a good robustness performance on resisting the deception attacks.

Adaptive Containment Control for Heterogeneous MIMO Nonlinear Multiagent Systems With Unknown Direction Actuator Faults

In this article, a novel output-feedback adaptive containment control scheme is proposed for a class of heterogeneous multi-agent systems, where the agents are nonlinear multi-input multi-output (MIMO) systems whose relative degrees are allowed to be different. Unlike existing results, we only require the leading principal minors of agents' control gain matrices (CGMs) to be nonzero and take into account unknown direction actuator faults, which relaxes the restrictions on CGMs and enhances system reliability. The difficulties jointly caused by the unknown CGMs, unknown parameters, and unknown jumps introduced by the actuator faults are successfully overcome by a novel recursive contradiction argument based on some Nussbaum functions and a matrix similarity transformation. Moreover, an event-triggering mechanism is introduced to avoid continuous communication among agents and reduce the communication burden. It is shown that all closed-loop signals are globally uniformly bounded and the containment errors converge to a residual set that can be made arbitrarily small. Simulation results illustrate the effectiveness of the proposed scheme.

Hierarchical Hybrid Control for Scaled Consensus and Its Application to Secondary Control for DC Microgrid.

This article addresses the scaled consensus problem for a class of heterogeneous multiagent systems (MASs) with a cascade-type two-layer structure. It is assumed that the information of the upper layer state components is intermittently exchangeable through a strongly connected communication network among the agents. A distributed hierarchical hybrid control framework is proposed, which consists of a lower layer controller and an upper layer one. The lower layer controller is a decentralized continuous feedback controller, which makes the lower layer state components converge to their target values. The upper layer controller is a distributed impulsive controller, which enforces a scaled consensus for the upper layer state components. It is proved that the two layer controllers can be designed separately. By considering the dwell-time condition of impulses and the feature of the strongly connected Laplacian matrix, a novel weighted discontinuous function is constructed for scaled consensus analysis. By using the Lyapunov function, a sufficient condition for scaled consensus of the MAS is derived in terms of linear matrix inequalities. As an application of the proposed distributed hybrid control strategy, a relaxed distributed hybrid secondary control algorithm for dc microgrid is obtained, by which the balance requirement on the communication digraph is removed, and an improved current sharing condition is obtained.

Sampled-Data Consensus Protocols for a Class of Second-Order Switched Nonlinear Multiagent Systems.

In this study, the sampled-data consensus problem is investigated for a class of heterogeneous multiagent systems (MASs) in which each agent is described by a second-order switched nonlinear system. Owing to the heterogeneity and the occurrence of dynamic switching in the MASs, the sampled-data consensus protocol design problem is challenging. In this study, two periodic sampled-data consensus protocols and an event-triggered consensus protocol are developed. Here, we first propose a new periodic sampled-data consensus protocol that involves the local objective trajectory interaction among agents. The protocol is then improved by applying the finite-time control and sliding-mode control techniques. Notably, the improved protocol can be implemented without the transmission of constructed auxiliary dynamical variables, which is a major feature of the present study. It is shown that complete consensus of the underlying MASs can be achieved by the two proposed protocols with only sampled-data measurements. To further reduce the communication load, we introduce an event-triggered mechanism to obtain a new protocol. Finally, the effectiveness of the given schemes is demonstrated by considering a numerical example.

Finite-time group consensus via pinning control for heterogeneous multi-agent systems with disturbances by integral sliding mode

In this paper, the finite-time group consensus for a class of heterogeneous multi-agent systems (HMASs) with bounded disturbances is studied by designing a pinning control scheme with an integral sliding mode. For an HMAS without disturbance, a continuous finite-time consensus protocol with a pinning and grouping strategy is proposed. Under the designed control protocol, the HMAS achieves consensus according to the given grouping requirement in a finite time and the final states converge to the desired consistency values. The detailed theoretical proof is given on the strength of Lyapunov theory, LaSalle’s invariance principle and homogeneity with dilation principle. On this basis, this paper further introduces an integral sliding mode into finite-time group consensus protocol designed above such that the HMAS with one or more pinning agents can achieve accurate finite-time group consensus even if there exist uncertain bounded disturbances. It is noted that the control input is chattering-free. Two simulation examples are presented to illustrate the effectiveness of the proposed control schemes.

Observer‐based consensus control for heterogeneous multi‐agent systems with intermittent communications

AbstractIn this article, the output consensus tracking problem for a class of heterogeneous multiagent systems (HMASs) with intermittent communications is studied. We first design a local observer for each agent to estimate unmeasurable state information of followers', and an adaptive distributed estimator is constructed for each follower to estimate the leader's state. Then a type of switched and distributed tracking controllers for HMASs are established under the intermittent communications, and relative parameters of the novel controllers are designed via the constructed regulation equation. Furthermore, by using the switching system theory and LMI technology, both the sufficient conditions for HMASs to achieve output consensus tracking and the threshold of communication rate are obtained, and simultaneously the controller gain and observer gain matrices are constructed. Finally, a simulation example is provided for general HMASs to verify the correctness and effectiveness of the proposed method.

Distributed type‐2 fuzzy adaptive control for heterogeneous nonlinear multiagent systems

AbstractA novel type‐2 fuzzy adaptive consensus control is studied for a class of heterogeneous multiagent systems with identical or nonidentical dimensions. At first, the similar composite structure for a class of heterogeneous multiagent systems with identical or nonidentical dimensions is introduced. Some similar parameters among each agent are defined that can be obtained by calculating the proposed similar properties. Second, according to the graph theory and Lyapunov stability, a novel distributed type‐2 fuzzy adaptive control with similar parameters is constructed for the consensus of nonlinear heterogeneous multiagents with different dimensions, in which all signals can converge to small zero fields. Finally, two simulation examples are addressed for the considered systems to show the effectiveness of the control scheme, and some merits of the control approach are also demonstrated by comparison of similar control.

Event-Triggered Formation Control and Leader Tracking With Resilience to Byzantine Adversaries: A Reputation-Based Approach

A distributed event-triggered controller is developed for formation control and leader tracking (FCLT) with robustness to adversarial Byzantine agents for a class of heterogeneous multi-agent systems (MASs). Assuming each agent can accurately measure the state of a neighbor whenever the neighbor broadcasts its state, a reputation-based strategy is developed for each agent to detect Byzantine agent behaviors within their neighbor set and then selectively disregard Byzantine state information. Selectively ignoring Byzantine agents results in a time-varying graph topology. Nonsmooth dynamics also result from intermittent communication due to an event-triggered strategy, which facilitates the efficient use of resources. Nonsmooth Lyapunov methods are used to prove stability and FCLT of the MAS consisting of the remaining cooperative agents.

Dynamic group consensus for delayed heterogeneous multi-agent systems in cooperative-competitive networks via pinning control

Distinguished from the stationary group consensus problem, in this paper, the dynamic group consensus for a class of heterogeneous multi-agent systems under the influence of input time delays is investigated. A novel dynamic group consensus protocol is designed, where the coexisted cooperation and competition interaction relationships among the agents are considered. Two cases including identical and diverse input time delays are discussed, respectively. Based on matrix theory, system stability theory and pinning control strategy, some sufficient conditions for the heterogeneous systems are established to achieve dynamic group consensus asymptotically. The obtained results reveal that the achievement of systems’ dynamic group consensus is related to systems control parameters, the in-degree and input time delays of the agents. Finally, the effectiveness of our theoretical results is verified by some numerical simulations.

Distributed Fuzzy Adaptive Consensus Control for a Class of Heterogeneous Multi-agent Systems with Nonidentical Dimensions

A novel distributed fuzzy adaptive control approach is studied for a class of heterogeneous uncertain nonlinear multi-agent systems with different dimensions. Similar definition and property of each agent are introduced, and similar parameters among each agent can be obtained using the proposed properties, then the feedback distributed fuzzy adaptive control based on similar matrices and vectors is designed such that all followers can asymptotically track the leader’s dynamic behaviors. It is proved that the consensus problem of heterogeneous nonlinear multi-agent systems with different dimensions can be guaranteed by applying the proposed control strategy. An efficient framework is that the computation burden can be alleviated greatly because of a few adaptive laws. Finally, two simulation examples are provided to verify the effectiveness of the designed control method.

Semiglobal Consensus of a Class of Heterogeneous Multi-Agent Systems With Saturation.

This article addresses the leader-following consensus of a class of multi-agent systems (MASs) subjected to saturation. Unlike previous literature, the followers are with heterogeneous dynamics. To solve this problem, we employ the low-gain feedback technique and the parameterized algebraic Riccati equations to design the controllers. For the fixed and switching network topologies, sufficient conditions are put in place to guarantee the semiglobal stability of the consensus error system. Numerical results are also provided to validate the effectiveness of the control design.

Finite-time consensus of heterogeneous unknown nonlinear multi-agent systems with external disturbances via event-triggered control

This article investigates the practical finite-time consensus for a class of heterogeneous multi-agent systems composed of first-order and second-order agents with heterogeneous unknown nonlinear dynamics and external disturbances in an undirected communication topology. To reduce the system updates, we propose an event-triggered approach. By defining auxiliary states, an adaptive distributed event-triggered control is designed to achieve practical finite-time consensus. Unknown nonlinear dynamics for each agent are estimated using radial basis function neural network. The stability of the overall closed-loop system is studied through the Lyapunov criterion. It is proven that by applying the proposed control scheme, the local neighbor position error and the velocity error between any two agents converge to a small region in finite time. Furthermore, it is shown that the Zeno behavior is ruled out. Finally, applicability and effectiveness of the proposed control scheme is verified and validated by two examples.

Distributed Fuzzy Adaptive Control for Heterogeneous Nonlinear Multiagent Systems with Similar Composite Structure

A distributed fuzzy adaptive control with similar parameters is constructed for a class of heterogeneous multiagent systems. Unlike many existing works, the dimensions of each multiagent dynamic system are considered to be nonidentical in this paper. Firstly, similar properties for different dimensions of multiagent systems are introduced, and some similar parameters among multiagent systems are also proposed. Secondly, a distributed fuzzy adaptive control on the basis of similar parameters is designed for the consensus of leader-follower multiagent systems. Following the graph theory and Lyapunov stability approach, it is concluded that UUB (uniformly ultimately bounded) of all signals in the closed-loop system can be guaranteed, and the consensus tacking error converges to a small compact zero set. Finally, a simulation example with different dimensions is provided to illustrate the effectiveness of the proposed method.

Group consensus via pinning control for a class of heterogeneous multi-agent systems with input constraints

This paper studies group consensus for a class of heterogeneous multi-agent systems (HMASs), where the dynamics of agents are described by single and double integrators. First, under the case that all the agents’ control inputs are bounded and the second-order agents’ velocity information cannot be obtained, we design controllers with a grouping and pinning scheme by introducing an auxiliary function. With the help of Lyapunov theory, it is proved that an HMAS with some pinning agents can achieve group consensus asymptotically under an undirected connected topology and the final states of all agents can converge to the desired consensus values. Furthermore, we investigate group consensus for an HMAS under multiple communication constraints, where the dynamics of the second-order agents are represented by linear and Euler–Lagrange (EL) nonlinear dynamics. Two control protocols and group consensus criteria are also provided to guarantee that the HMAS with or without uncertain parameters can reach group consensus. Finally, two simulation examples illustrate the obtained results.

Robust Distributed Stabilization of Heterogeneous Agents Over Cooperation–Competition Networks

Distributed stabilization problem is investigated in this brief for a class of heterogeneous multi-agent systems (MASs) in the presence of exogenous disturbances and cooperation-competition interactions. Specifically, the dynamics of the heterogeneous agents are governed by the second-order systems with the nonlinear intrinsic dynamics where the heterogeneity of agents is mainly reflected in the following three aspects: the intrinsic dynamics of agents, the heterogeneous velocity damping terms, and the exogenous disturbances. With the assumption that the exogenous disturbances are bounded, a discontinuous distributed protocol associated with a time-varying estimator of the agent are designed. Then, with the help of the LaSalle-Yoshizawa theorem for nonsmooth system and the Barbalat’s lemma, it is proved that no matter whether the network topology is structurally balanced or not, the heterogeneous MASs can achieve robust distributed stabilization asymptotically as long as the control parameters of the distributed protocol are chosen appropriately. Finally, the derived analytical results are demonstrated by performing a numerical example.

Couple-Group Consensus: A Class of Delayed Heterogeneous Multiagent Systems in Competitive Networks

This paper discusses the couple-group consensus issues of a class of heterogeneous multiagent systems containing first-order and second-order dynamic agents under the influence of both input and communication delays. In distinction to the existing works, a novel distributed coordination control protocol is proposed which is not only on the foundation of the competitive interaction between the agents but also has no virtual velocity estimation in the first-order dynamics. Furthermore, without the restrictive assumptions existing commonly in the related works, several sufficient algebraic criteria are established for the heterogeneous systems to realize couple-group consensus asymptotically. The obtained conclusions show that the achievement of the systems’ couple-group consensus intimately relates to the coupling weights between the agents, the systems control parameters, and the input time delays of the agents, while communication time delays between the agents are irrelevant to it. Finally, several simulations are illustrated to verify the effectiveness of the obtained theoretical results.