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The robust tracking control problem of the leader‐follower multiagent systems affected by asymmetric input saturation and external disturbances is addressed in this article, by following three steps. First, an radial basis function neural network (RBFNN) is developed to estimate the external disturbances and supersaturation, where the supersaturation is induced by asymmetric saturation actuator. Second, combining with the developed radial basis function neural network, a reduced‐order observer‐based static protocol and a reduced‐order observer‐based adaptive one are designed for leader‐follower systems with un‐directed communication topology as well as those with directed communication topology, respectively. Third, some mild premises are given to guarantee the semiglobal robust leader‐follower consensus for the above mentioned two kinds of multiagent systems. Finally, the theoretical results are verified by several numerical simulations. [ABSTRACT FROM AUTHOR]

Most of the existing studies on controllability have only focused on networks with non‐negative weighted interactions/edges among agents. In fact, there are both positive and negative weighted interactions in a network, where positive/negative weight implies cooperative/antagonistic interaction. The controllability of leader‐based multi‐agent systems described by directed/undirected signed graphs is respectively considered for fixed topology and switching topology. A quantitative characterization of controllability is given based on the influence pattern of leaders and some algebraic and graphical features of controllability are established according to consensus protocols. Moreover, it is proved that all follower agents can be steered to the desired configuration under structurally balanced conditions. Specially, a simultaneously structurally balanced signed multiagent network can be controllable on switching topology even though each subnetwork is uncontrollable. Finally, several numerical examples and simulation results are given. [ABSTRACT FROM AUTHOR]

In this article, the problems of inverse-optimal consensus control (IOCC) for single-integral dynamics in Caputo continuous-time and Grunwald–Letnikov (G-L) discrete-time fractional-order multiagent systems (FOMASs) are investigated. For continuous-time FOMASs, by virtue of the variational method, the optimal solution under the constraint of the global performance index function is presented, and then the optimal state-feedback gain matrix (OSFGM) is derived through the Laplace transform and the inverse transform of fractional order. For discrete-time FOMASs, the OSFGM based on the algebraic Riccati equation (ARE) is computed, then it is shown that the OSFGM is a (asymmetric) Laplace matrix which has a zero eigenvalue and the corresponding network structure is a complete graph. Moreover, we rigorously prove that consensus can be achieved under the optimal state-feedback gain matrices. Finally, two simulation examples are shown to check the validity of the proposed theorems. [ABSTRACT FROM AUTHOR]

In this article, we study the consensus issues of multiagent systems (MASs) without any information of the system model by using the reinforcement learning (RL) method and event-based control strategy. First, we design an adaptive event-based consensus control protocol using the local sampled state information so that the consensus errors of all agents are uniformly ultimately bounded. The validity of the above event-triggered adaptive control protocol is confirmed by excluding the Zeno behavior within finite time. Then, based on the RL approach, we present a model-free algorithm to get the feedback gain matrix, and accomplish constructing the adaptive event-triggered control strategy without the knowledge of model information. Distinct with the existing related works, this RL-based event-triggered adaptive control algorithm only relies on the local sampled state information, irrelevant to any model information or global network information. Finally, we provide some examples to demonstrate the validity of the above adaptive event-based consensus algorithm. [ABSTRACT FROM AUTHOR]

This article studies the consensus control problem of second-order multiagent systems with switching dynamics, which consist of a continuous-time and a discrete-time subsystem. A novel control protocol is proposed for fixed digraphs by using the same control strategy for two subsystems so that the controller can keep the control strategy unchanged when systems switch. Moreover, this control strategy uses only sampled position data at the current sampling time and the previous sampling time to deal with this possible situation when speed information is difficult to be measured, which is also robustness and low cost. Some necessary and sufficient conditions to achieve consensus are derived about the network topology, structure and sampling period. At last, a few simulation examples are given. [ABSTRACT FROM AUTHOR]

In this article, bipartite consensus is investigated for linear multi‐agent systems (MASs) via adaptive asynchronous intermittent control. Adaptive asynchronous intermittent bipartite consensus protocols are proposed for MASs with antagonistic links under both fixed and connected switching topologies. By using gauge transformation and stability theory, convergency analysis is given and some conditions of bipartite consensus are obtained. It is turned out that bipartite consensus can be realized if the communication rate is no less than a threshold under the assumption that the network is connected and structurally balanced. Finally, two simulation examples are provided to verify the effectiveness of the obtained results. [ABSTRACT FROM AUTHOR]

A consensus control issue is studied for general second-order multiagent systems via Q-learning method in this article. A novel second-order type with discrete-time dynamics is investigated to solve the corresponding consensus issues. Under fixed directed topology, in order to achieve general second-order consensus for the systems, a model-free Q-learning method is proposed, which can derive the coupling gains matrix without any information from the system dynamics. Moreover, applying the obtained coupling gains matrix, this general second-order multiagent systems can achieve consensus. Then, for undirected graphs, a similar corollary is obtained for this system to achieve general second-order consensus by means of the Q-learning method. Finally, the correctness of the new method is confirmed by several simulation examples. [ABSTRACT FROM AUTHOR]

This article proposes a $Q$ -learning (QL)-based algorithm for global consensus of saturated discrete-time multiagent systems (DTMASs) via output feedback. According to the low-gain feedback (LGF) theory, control inputs of the saturated DTMASs can avoid the saturation by utilizing the control policies with LGF matrices, which were computed from the modified algebraic Riccati equation (MARE) by requiring the information of system dynamics in most previous works. However, in this article, we first find the lower bound on the real part of Laplacian matrices’ nonzero eigenvalues of directed network topologies. Then, we define a test control input and propose a $Q$ -function to derive a QL Bellman equation, which plays an essential part of the QL algorithm. Subsequently, different from the previous works, the output-feedback gain (OFG) matrix of this article can be obtained by limited iterations of the QL algorithm without requiring the information of agent dynamics and network topologies of the saturated DTMASs. Furthermore, the saturated DTMASs can achieve global consensus rather than the semiglobal consensus of the previous results. Finally, the effectiveness of the QL algorithm is confirmed via two simulations. [ABSTRACT FROM AUTHOR]

In this article, we propose two model-free algorithms using state or output feedback for saturated discrete-time multiagent systems (SDTMASs) to attain global containment control. In most previous works, the control input can avoid saturation by utilizing the low gain feedback (LGF) method whereas requiring the knowledge of agent dynamics, and SDTMASs just can attain semi-global containment control. Distinct with the previous works, first, based on the $Q$ -learning (QL) technique, this article defines a $Q$ -function and deduces the corresponding QL Bellman equation, which is the most important part of the QL algorithm. Then, in order to solve the QL Bellman equation, we propose two iterative model-free algorithms using state and output feedback, and the LGF matrix can be acquired from that solution directly. Furthermore, under the state and output feedback control protocols with the feedback matrices obtained from the proposed model-free algorithms, the SDTMASs can achieve global containment control instead of semi-global containment control. Finally, we present some simulations to confirm the validity of the proposed algorithms. [ABSTRACT FROM AUTHOR]

This article studies the flocking problem of multiagent systems (MASs) with a dynamic virtual leader (VL) for the linear systems subject to time-varying uncertainties and external disturbance problems. We assume that the agents follow a leader with a bounded acceleration, which information is sensed only by the informed agents. We assign an adaptive estimator to each uninformed agent to estimate the velocity of the leader. By deriving a lemma and using a standard adaptive law, we design a continuous adaptive controller for solving the problem under the mentioned challenges, which is also fully distributed. The designed flocking control ensures that the velocity of followers asymptotically is converged to that of the VL. Also, the agents’ network remains connected, and no collision occurs among agents. Finally, we present a simulation that illustrates the validity of the results. [ABSTRACT FROM AUTHOR]

This essay considers the bipartite consensus of matrix-weighted second-order multi-agent systems with structurally unbalanced antagonistic interactions networks. Owing to the influence of matrix-weights, bipartite consensus and cluster bipartite consensus can also be reached, which is different from the existing works on signed networks. With the assistance of Lyapunov stability and matrix-valued Gauge transformation, a condition to achieve bipartite consensus is established. Moreover, a relatively straightforward algebraic graph condition for reaching cluster bipartite consensus is attained. Finally, simulation examples are supplied to illustrate the obtained results. • The bipartite consensus of MASs is investigated for structurally unbalanced matrix-weighted signed networks. • The MASs can be reached bipartite consensus and cluster bipartite consensus. • All the clusters can be obtained by designing matrix weights. [ABSTRACT FROM AUTHOR]

The containment control problem in fractional-order multiagent systems over a directed graph is studied in this article. Two distributed control protocols with or without time delays are designed by utilizing the sampled position and velocity data. Then, based on the knowledge of the matrix theory and Laplace transform, some necessary and sufficient conditions to reach containment are derived. For the protocol with time delays, similar sufficient and necessary conditions are obtained. Finally, some simulation examples are designed to verify that the theorems are correct. [ABSTRACT FROM AUTHOR]

This paper considers the positive consensus of fractional-order multi-agent systems described by general linear dynamics with the fractional order belonging to (0, 2) via state feedback. Firstly, the distributed positive consensus protocols are given, and then, the necessary and sufficient conditions are gained for the consensus with positive constraint based on the fractional-order stability theory as well as the features of Metzler matrix. Furthermore, some sufficient positive consensus conditions are provided and are reduced to the conditions without the global networked information for the system with α ∈ (0 , 1 ] . Finally, illustration examples are provided to indicate not only the validity but also the superiority of the presented approach, compared with the highly related methods. [ABSTRACT FROM AUTHOR]

This article studies the consensus of hybrid second-order multiagent systems (MASs), where the hybrid MAS is constituted by the continuous-time second-order (CTSO) and discrete-time second-order (DTSO) dynamic agents. First, a hybrid consensus algorithm is proposed, where a sample-data control is considered in the CTSO subsystems. Under the proposed hybrid consensus algorithm, the convergence of the hybrid second-order MAS matrix is analyzed. Second, a sufficient and necessary condition is proposed, which indicates that the controller parameters, such as coupling gains and the sampling interval, and eigenvalues of network topology have a significant impact on the system consensus. Finally, several simulation examples are presented to prove the validity of the results. [ABSTRACT FROM AUTHOR]

• Controllability of matrix-weighted multi-agent systems is investigated. • Antagonistic interactions exist in the multi-agent systems. • Structurally balanced graphs are used in the design and analysis. • The uncontrollable conditions are also discussed. This study aims at the controllability of multi-agent systems (MASs) with cooperation and competition in a matrix-weight-based signed network based on the leader-follower structure from an algebra-theoretic perspective, which is a generalization of a scalar-weighted signed network due to increasing the dimension of controllable matrix and controllable subspace for such MASs. Therefore, comparing with existing results, relying on matrix coupling links, the study indicates that controllability can be attained in a structurally balanced matrix-weight-based network. Algebra-theoretic characterizations for attaining controllability are provided. Moreover, the algebraic uncontrollable conditions for such network are examined. Examples and simulations are given to illustrate the theoretical results. [ABSTRACT FROM AUTHOR]

This paper is concerned with consensus for fractional-order multi-agent systems by observer-type output feedback with positive constraint depicted by general linear model. First, an observer-based protocol is presented and the sufficient conditions for the consensus for fractional-order multi-agent systems with positive constraint are derived. Then, the simplified conditions without utilizing the detailed topology of the graph are given. In order to simplify the process of the solution of the feedback gain matrix and the observer gain matrix, the linear programming approach is used. When the system matrix is strictly Metzler, semidefinite programming approach is adopted. Finally, some illustration examples are presented as the verification of the obtained methods. [ABSTRACT FROM AUTHOR]

In this paper, the consensus problem of a continuous-time uncertain multi-agent system (MAS) with time-varying interval uncertainties in the system matrix and unknown initial states is investigated via output feedback. Relating only to the interval bounds on the uncertainties, a reduced-order framer, which includes two Luenberger-like observers, is first derived. Then, a distributed control algorithm relying only on the information of the framers associated with each agent and its neighbors is proposed. It is shown that the control algorithm can render the reduced-order framer to be an exponential reduced-order interval observer, and simultaneously drive the uncertain MAS to reach robust consensus exponentially. Finally, numerical simulations for a large-scale MAS are used to verify the theoretical results. [ABSTRACT FROM AUTHOR]

This paper investigates flocking problems with uncertain nonlinear multi-agent systems. Two distributed adaptive event-triggered control algorithms are proposed for leaderless and leader-follower flocking, separately. According to Lyapunov stability theory, under the proposed control protocols, we obtain some sufficient conditions to ensure stable flocking motion and maintain connectivity of network topology. And it is proven that there is a positive lower limit of the interval between any two trigger events, which indicates that the Zeno behavior will not occur. As a result, communication bandwidth resources are effectively saved on the premise of stable flocking. Lastly, numerical simulations are presented to verify the availability of the theoretical results. [ABSTRACT FROM AUTHOR]