Showing papers on "Consensus published in 2021"
TL;DR: It is proved that the designed method can guarantee that all the signals in the closed-loop systems are bounded in probability, and the distributed consensus tracking errors can converge to a small neighborhood of the origin via the Lyapunov stability theory.
Abstract: This article studies the distributed observer-based event-triggered bipartite tracking control problem for stochastic nonlinear multiagent systems with input saturation. First, different from conventional observers, we construct a novel distributed reduced-order observer to estimate unknown states for the stochastic nonlinear systems. Then, an event-triggered mechanism with relative threshold is introduced to reduce the burden of communication. In addition, the bipartite tracking controller is proposed for stochastic multiagent systems by using fuzzy logic systems and the backstepping approach. Meanwhile, it is proved that the designed method can guarantee that all the signals in the closed-loop systems are bounded in probability, and the distributed consensus tracking errors can converge to a small neighborhood of the origin via the Lyapunov stability theory. Finally, a simulation example is given to prove the effectiveness of the designed scheme.
255 citations
TL;DR: A minimum cost model based on robust optimization is proposed to solve the robust optimization consensus problem of LSGDM, considering the social relationship between experts.
126 citations
TL;DR: It is shown that the consensus protocol design problem can be transformed into two static output feedback (SOF) control problems and that the SOF controller gains can be determined by solving some linear matrix inequalities without the knowledge of the probability information of each attack.
Abstract: This paper investigates the leader–follower robust ${H_\infty }$ consensus of heterogeneous multiagent systems with denial of service attack, where different attack intensities are considered. A switched system model is introduced to model such an attack phenomenon. Then, sufficient conditions to guarantee the solvability of the robust output consensus problem are obtained, and the quantitative relationship between the consensus performance and attack parameter is established. It is shown that the consensus protocol design problem can be transformed into two static output feedback (SOF) control problems. It is also shown that the SOF controller gains can be determined by solving some linear matrix inequalities without the knowledge of the probability information of each attack. Finally, the effectiveness of the control protocol is demonstrated by a simulation study.
119 citations
TL;DR: In this paper, the sampled-based consensus problem is investigated for a class of nonlinear multiagent systems subjected to deception attacks and the eigenvector of Laplacian matrix is utilized to construct a novel Lyapunov functional.
Abstract: In this paper, the sampled-based consensus problem is investigated for a class of nonlinear multiagent systems subjected to deception attacks. Due to network fluctuations and limited resources, deception attacks might destroy the sampled-data in communication networks. Additionally, the success of deception attacks greatly depends on some randomly fluctuated factors. This paper takes into account the deception attacks that are randomly launched at each sampling instant. The eigenvector of Laplacian matrix is utilized to construct a novel Lyapunov functional. Then, the decoupled criterion connected with eigenvalues of Laplacian matrix is obtained such that the addressed multiagent systems achieve the mean square consensus. Furthermore, the solutions of a set of matrix inequalities represent the controller gain matrix. Finally, a numerical example is provided to validate the effectiveness of the derived results.
111 citations
TL;DR: It is shown that the consensus problem for heterogeneous multiagent systems with nonuniform communication delays can be solved by the proposed method and an illustrative example is provided to verify the effectiveness of the developed method.
Abstract: This article is concerned with the event-triggered output consensus problem for heterogeneous multiagent systems (MASs) with nonuniform communication delays. Unlike the existing event-triggered consensus results, more general heterogeneous linear MASs and nonuniform communication delays are considered. To reduce communication among subsystems, novel dynamic periodic event-triggered mechanisms are proposed. By using the event-triggered signals at the previous sampling instant, new distributed observers are designed to eliminate asynchronous behavior caused by nonuniform communication delays. Based on the developed observers, the observer error system is converted into a time-delay system with interval time-varying delays. Besides, a controller is designed by using the states of observers. It is shown that the consensus problem can be solved by the proposed method. Finally, an illustrative example is provided to verify the effectiveness of the developed method.
105 citations
TL;DR: In this article, the bipartite fixed-time output consensus problem of heterogeneous linear multiagent systems (MASs) is investigated, and a distributed bipartitite fixed time observer is proposed, by which the follower can estimate the leader's state.
Abstract: In this article, the bipartite fixed-time output consensus problem of heterogeneous linear multiagent systems (MASs) is investigated. First, a distributed bipartite fixed-time observer is proposed, by which the follower can estimate the leader’s state. The estimate value is the same as the leader’s state in modulus but may not in sign due to the existence of antagonistic interactions between agents. Then, an adaptive bipartite fixed-time observer is further proposed. It is fully distributed without involving any global information. This adaptive bipartite fixed-time observer can estimate not only the leader’s system matrix but also the leader’s state. Next, distributed nonlinear control laws are developed based on two observers, respectively, such that the bipartite fixed-time output consensus of heterogeneous linear MASs can be achieved. Moreover, the upper bound of the settling time is independent of initial states of agents. Finally, the examples are given to demonstrate the results.
98 citations
TL;DR: In this article, a review is conducted on the recent development of MASs intended for intelligent control, including consensus problem, formation control, and flocking control, based on the limitations of the interaction level and the constraints of the individual system level.
Abstract: In practice, the dual constraints of limited interaction capabilities and system uncertainties make it difficult for large-scale multiagent systems (MASs) to achieve intelligent collaboration with incomplete local relative information. In this article, a review is conducted on the recent development of MASs intended for intelligent control, including consensus problem, formation control, and flocking control. Based on the limitations of the interaction level and the constraints of the individual system level, the published results on intelligent control are categorized into limited sensing-based control, event-based control, pinning-based control, resilient control, and collaborative control under system constraints. Also, the applications of intelligent control for MASs are presented, especially for robotics, complex networks, and transportation. Finally, a discussion is given about the challenges and future directions of research in this field.
90 citations
TL;DR: It is shown that the proposed control scheme achieves fixed-time leader–follower consensus of the studied MAS with output constraints, unknown control direction, unknown system dynamics, and unknown external disturbance.
Abstract: This article is concerned with fixed-time leader–follower consensus problem for multiagent systems (MASs) with output constraints, unknown control direction, unknown system dynamics, unknown external disturbance, and dead-zone control input. First, a fixed-time distributed observer is presented for each follower to estimate the leader’s states. Next, using a modified nonlinear mapping, an output-constrained system is transformed into an unconstrained system. Then, by adopting adding a power integrator technique, radial basis function neural network (RBFNN) approximation, and adaptive method, the ideal fixed-time stable virtual control protocol is derived and the issues of unknown control direction, unknown system dynamics, and unknown external disturbance are addressed. Finally, the actual control protocol is developed using the bound of dead-zone parameters. It is shown that the proposed control scheme achieves fixed-time leader–follower consensus of the studied MAS. The presented control protocol is applied to the leader–follower consensus of inverted pendulums and simulation results verify its effectiveness.
88 citations
TL;DR: It is proven that the consensus tracking control objective can be achieved for multiagent systems suffering from actuator faults and arbitrary switchings.
Abstract: In this article, the distributed fault-tolerant consensus tracking control problem is investigated for a class of nonlinear multiagent systems, where the dynamics of agents are heterogeneous and switched. For the subsystems of each agent, nonlinear terms are not required to satisfy any growth conditions and fuzzy logic systems are employed to approximate unknown functions. In the protocol design, information on the interaction topology and the number of agents cannot be used. Since the underlying multiagent systems are heterogeneous and have switching characteristics, and the topology information is unknown, it is rather difficult to solve the consensus tracking problem using existing algorithms. In this article, a novel distributed consensus tracking protocol is developed. By using the graph theory, Lyapunov functional method and fuzzy logic systems approximation technique, it is proven that the consensus tracking control objective can be achieved for multiagent systems suffering from actuator faults and arbitrary switchings. Finally, to demonstrate the validity of the developed methodology, a numerical simulation is presented.
81 citations
TL;DR: Graph theory, nonsmooth analysis, convex analysis, and the Lyapunov theory are employed to show that the proposed algorithms converge accurately to the optimal solution of the considered problem.
Abstract: In this article, we consider the distributed optimal consensus problem under nominal and nonfragile cases for a class of minimum-phase uncertain nonlinear systems with unity-relative degree and disturbances generated by an external autonomous system. The involved cost function is the sum of all local cost functions associated with each individual agent. Two different edge-based distributed adaptive algorithms utilizing the internal model principle are designed to solve the problem in a fully distributed manner. Graph theory, nonsmooth analysis, convex analysis, and the Lyapunov theory are employed to show that the proposed algorithms converge accurately to the optimal solution of the considered problem. Finally, an example involving the dynamics of a Lorenz-type system is provided to demonstrate the effectiveness of the obtained results.
72 citations
TL;DR: A singularity-free sliding mode control law is designed to solve the fixed-time-synchronized consensus problem and is presented as a special kind of fixed/finite-time stability, where all the elements of the system state synchronously arrive at the equilibrium at the same time.
Abstract: In this article, a unique multiagent control problem is defined—all the elements of all the agent states reaching consensus at the same time, i.e., the multiagent system achieves time-synchronized consensus and fixed-time-synchronized consensus, where the upper bound of the synchronized settling time is independent of the initial states of multiagent systems. To articulate this (fixed-) time-synchronized consensus problem, we first propose time-synchronized stability and fixed-time-synchronized stability, a special kind of fixed/finite-time stability, where all the elements of the system state synchronously arrive at the equilibrium at the same time, with the upper bound of the synchronized settling time dependent/independent of initial conditions. Based on fixed-time-synchronized stability, a singularity-free sliding mode control law is designed to solve the fixed-time-synchronized consensus problem. Finally, numerical simulations are conducted to showcase the effectiveness, and further exploration of the merit of the proposed controller is provided.
TL;DR: In this article, a distributed fault-tolerant resilient consensus problem for heterogeneous multiagent systems (MASs) under both physical failures and network denial-of-service (DoS) attacks is considered.
Abstract: In this article, we consider the distributed fault-tolerant resilient consensus problem for heterogeneous multiagent systems (MASs) under both physical failures and network denial-of-service (DoS) attacks. Different from the existing consensus results, the dynamic model of the leader is unknown for all followers in this article. To learn this unknown dynamic model under the influence of DoS attacks, a distributed resilient learning algorithm is proposed by using the idea of data-driven. Based on the learned dynamic model of the leader, a distributed resilient estimator is designed for each agent to estimate the states of the leader. Then, a new adaptive fault-tolerant resilient controller is designed to resist the effect of physical failures and network DoS attacks. Moreover, it is shown that the consensus can be achieved with the proposed learning-based fault-tolerant resilient control method. Finally, a simulation example is provided to show the effectiveness of the proposed method.
TL;DR: In this article, a fault-tolerant consensus control of a general nonlinear multi-agent system subject to actuator faults and disturbed and faulty networks is proposed by using neural network (NN) and adaptive control techniques.
Abstract: This article addresses the problem of fault-tolerant consensus control of a general nonlinear multiagent system subject to actuator faults and disturbed and faulty networks. By using neural network (NN) and adaptive control techniques, estimations of unknown state-dependent boundaries of nonlinear dynamics and actuator faults, which can reflect the worst impacts on the system, are first developed. A novel NN-based adaptive observer is designed for the observation of faulty transformation signals in networks. On the basis of the NN-based observer and adaptive control strategies, fault-tolerant consensus control schemes are designed to guarantee the bounded consensus of the closed-loop multiagent system with disturbed and faulty networks and actuator faults. The validity of the proposed adaptively distributed consensus control schemes is demonstrated by a multiagent system composed of five nonlinear forced pendulums.
TL;DR: Under the designed triggering mechanisms and fully distributed edge-event-triggered adaptive consensus strategies, the MASs do not exhibit the Zeno behavior.
TL;DR: Lyapunov-based stability analysis and HDETM design are presented based on hybrid systems framework, and matrix inequality conditions are given to verify the consensus and $\mathcal {H}_{\infty }$ performance.
Abstract: This article addresses the event-triggered consensus problem of multiagent systems (MAS) with disturbances. Model-based control protocols are designed, and a hybrid dynamic event-triggering mechanism (HDETM) is proposed. Based on the proposed event-triggered control protocol, continuous communication between neighboring agents is not needed, and a prespecified strictly positive minimum ETI is guaranteed, i.e., Zeno behavior is excluded. A timer variable with jump dynamics is introduced to describe the HDETM in the closed-loop system. Then, a novel hybrid model is constructed for the closed-loop MAS, which contains both flow dynamics, and jump dynamics. Lyapunov-based stability analysis and HDETM design are presented based on hybrid systems framework, and matrix inequality conditions are given to verify the consensus and $\mathcal {H}_{\infty }$ performance. Finally, a spacecraft formation example is provided to show the effectiveness of the proposed methods.
TL;DR: A novel observer-based bipartite control scheme is developed on the basis of two event-triggering mechanisms that does not need continuous updates, avoids continuous communication between neighbors, and is applicable for the signed communication topology.
Abstract: This article investigates the bipartite consensus problem for linear multiagent systems by the event-triggered output feedback control scheme. Both cooperative interaction and antagonistic interaction between neighbor agents are considered. Assuming that the system states are not available for measurement, the state observer is thus proposed to settle this scenario. Then, a novel observer-based bipartite control scheme is developed on the basis of two event-triggering mechanisms. One is designed for the communication between neighbors and another is for controller updates. Different from the existing methods, the proposed control strategy does not need continuous updates, avoids continuous communication between neighbors, and is applicable for the signed communication topology. Moreover, we extend the results from the bipartite leaderless consensus to the bipartite leader-following consensus and the bipartite containment consensus. It is proven that the proposed controllers fulfill the exclusion of Zeno behavior in three consensus problems. Finally, three examples are provided to illustrate the feasibility of the theoretical results.
TL;DR: It is proved that bipartite output consensus for heterogeneous MASs can be guaranteed under structurally balanced graph under Lyapunov theory and output regulation technique.
Abstract: This brief deals with the bipartite output consensus problem for heterogeneous multi-agent systems (MASs) under antagonistic interactions. Two distributed controllers with state feedback control and output feedback control are designed, respectively. By virtue of the Lyapunov theory and the output regulation technique, it is proved that bipartite output consensus for heterogeneous MASs can be guaranteed under structurally balanced graph. Numerical examples are finally provided for demonstration of the validity of the derived results.
TL;DR: It is proved via an extension of the Lyapunov approach that ultimately bounded control is achieved for the leader-following consensus of the considered multiagent systems with unmeasurable states.
Abstract: In this article, the leader-following consensus problem via the event-triggered control technique is studied for the nonlinear strict-feedback systems with unmeasurable states. The follower’s nonlinear dynamics is approximated using the fuzzy-logic systems, and the fuzzy weights are updated in a nonperiodic manner. By introducing a fuzzy state observer to reconstruct the system states, an observer-based event-triggered adaptive fuzzy control and a novel event-triggered condition are designed, simultaneously. In addition, the nonzero positive lower bound on interevent intervals is presented to avoid the Zeno behavior. It is proved via an extension of the Lyapunov approach that ultimately bounded control is achieved for the leader-following consensus of the considered multiagent systems. One remarkable advantage of the proposed control protocol is that the control law and fuzzy weights are updated only when the event-triggered condition is violated, which can greatly decrease the data transmission and communication resource. The simulation results are provided to show the effectiveness of the proposed control strategy and the theoretical analysis.
TL;DR: Two pinning control algorithms are constructed for MASs, which not only reduce the number of controllers but also achieve expected tracking consensus andFixed-time group consensus is ensured by utilizing the algebraic graph theory, Lyapunov stability and fixed-time control technique.
Abstract: This paper deals with the fixed-time group consensus problem for multi-agent systems (MASs) subjected to exogenous disturbances. Firstly, two pinning control algorithms are constructed for MASs, which not only reduce the number of controllers but also achieve expected tracking consensus. Secondly, fixed-time group consensus is ensured by utilizing the algebraic graph theory, Lyapunov stability and fixed-time control technique. Finally, simulations are finally given for demonstrate the availability of the derived results.
TL;DR: In this paper, the finite-time output consensus problem is considered for a class of second-order multiagent systems (MASs), where the mismatched disturbance exists in the dynamics of each agent, and the communication topology is directed.
Abstract: In this paper, the finite-time output consensus problem is considered for a class of second-order multiagent systems (MASs), where the mismatched disturbance exists in the dynamics of each agent, and the communication topology is directed. First of all, a basic backstepping control protocol is proposed to solve the finite-time consensus problem without mismatched disturbance. Then, a finite-time disturbance observer is designed to estimate the mismatched disturbance, based on which, two adaptive finite-time consensus protocols are proposed to solve the finite-time output consensus and tracking consensus problems without using any global information with respect to the communication topology. Finally, two simulation examples are illustrated to verify the theoretical results.
TL;DR: In this paper, a leader-following bipartite consensus control strategy was proposed for uncertain nonlinear multiagent systems under a signed directed topology, where each follower has a time-varying gain by utilizing its relative output information.
Abstract: This paper concerns the predefined-time bipartite consensus control for uncertain nonlinear multiagent systems under a signed directed topology. All agents have high-order uncertain nonlinear dynamic characteristics satisfying a time-varying Lipschitz growth condition, and their partial state information is not available for measurement. In this case, we put forward a novel output-feedback-based predefined-time leader-following bipartite consensus control strategy. A predefined-time compensator for each follower is firstly constructed with a time-varying gain by utilizing its relative output information. Then, a novel linear-like output feedback predefined-time distributed control protocol is developed for each follower by means of the compensator. By making two artful state transitions, the bipartite consensus problem is reduced to a stabilization one of nonlinear systems. By means of the Lyapunov stability theorem, we strictly prove that the designed controllers can ensure that all agents realize bipartite consensus in predefined time. Finally, two simulation examples are given to validate the viability of the developed theoretical algorithm.
TL;DR: The optimal consensus problem of asynchronous sampling single-Integrator and double-integrator multiagent systems is solved by distributed model predictive control (MPC) algorithms proposed in this article.
Abstract: The optimal consensus problem of asynchronous sampling single-integrator and double-integrator multiagent systems is solved by distributed model predictive control (MPC) algorithms proposed in this article. In each predictive horizon, the finite-time linear–quadratic performance is minimized distributively by the control input with consensus state optimization. The MPC technique is then utilized to extend the optimal control sequence to the case of an infinite horizon. Conditions depending only on each agent’s weighting scalar and sampling step are derived to guarantee the stability of the closed-loop system. Numerical examples of rendezvous control of multirobot systems illustrate the efficiency of the proposed algorithm.
TL;DR: In this paper, a control scheme is designed to achieve the dynamic consensus for the multi-agent systems in directed topology interfered by stochastic noise, where a new distributed controller is designed based on Riccati inequalities.
Abstract: This paper investigates the consensus problem for linear multi-agent systems with the heterogeneous disturbances generated by the Brown motion. Its main contribution is that a control scheme is designed to achieve the dynamic consensus for the multi-agent systems in directed topology interfered by stochastic noise. In traditional ways, the coupling weights depending on the communication structure are static. A new distributed controller is designed based on Riccati inequalities, while updating the coupling weights associated with the gain matrix by state errors between adjacent agents. By introducing time-varying coupling weights into this novel control law, the state errors between leader and followers asymptotically converge to the minimum value utilizing the local interaction. Through the Lyapunov directed method and Ito formula, the stability of the closed-loop system with the proposed control law is analyzed. Two simulation results conducted by the new and traditional schemes are presented to demonstrate the effectiveness and advantage of the developed control method.
TL;DR: A new event-triggered communication scheme, based on designing a virtual system for each agent, is proposed to achieve the coordination task without velocity information to solve the consensus problem of multiple Euler–Lagrange systems subject to unavailable velocity information and limited communication resources.
Abstract: This article considers the consensus problem of multiple Euler–Lagrange systems subject to unavailable velocity information and limited communication resources. First, a new event-triggered communication scheme, based on designing a virtual system for each agent, is proposed to achieve the coordination task without velocity information. The event-triggering conditions only rely on the states of virtual systems and allow agents to transmit virtual states only at some discrete time instants. Under the proposed strategy, the control objective can be accomplished with lower communication and measurement costs. Second, we consider the time delay effects in each information channel with event-triggered communication. For the proposed event-triggered scheme, the Zeno triggering is excluded. Finally, two simulation examples with six two-linked robot manipulator arms are given to demonstrate the effectiveness of the proposed scheme.
TL;DR: It is proven that the practical leader-following consensus can be reached by the given control scheme and a numerical example is presented to show the effectiveness of the proposed protocol.
Abstract: In this note, the leader-following consensus problem is considered for a class of second-order nonlinear multiagent systems, where the communication topology is switching. In view of that the Lipschitz constants of nonlinear terms are unknown, adaptive control strategy is adopted. Using the back-stepping technique, a new adaptive protocol is proposed. It is noted that the global information, including the eigenvalues of Laplacian matrix, is not used in the protocol design. It is proven that the practical leader-following consensus can be reached by the given control scheme. Finally, we present a numerical example to show the effectiveness of the proposed protocol.
TL;DR: In this paper, the leader-follower consensus problem is investigated for feed-forward nonlinear time-delay multiagent systems under a fixed directed topology, and a novel static low-gain observer is first proposed for each follower by only utilizing the output information of the follower and its neighbor agents.
TL;DR: The leader-following consensus protocol based on dynamic gain method is proposed under the directed topology and an example on the multi-spacecraft system is provided to illustrate the effectiveness of the proposed methodology.
TL;DR: A decentralized consensus algorithm based on the blockchain technology for the solution of the Optimal Power Flow problem that maintains the convergence characteristics of the Alternating Direction Method of Multipliers iterative scheme and enables independent network nodes to reach consensus.
TL;DR: It is shown that the multiagent system can achieve consensus via nonlinear couplings provided the coupling strength surpasses a threshold, which depends on the smallest nonzero eigenvalue of the interaction graph Laplacian.
Abstract: This paper addresses the consensus problem of linear multiagent systems via nonlinear couplings. First, we show that the multiagent system can achieve consensus via nonlinear couplings provided the coupling strength surpasses a threshold, which depends on the smallest nonzero eigenvalue of the interaction graph Laplacian. Second, an adaptive coupling protocol is proposed to adjust the coupling strength without any usage of global information. Some numerical simulations are given to illustrate the effectiveness of the proposed protocols.
TL;DR: A new distributed controller is proposed, in which the control gains are designed as time-varying functions related to the pre-specified time and the validity of the designed schemes is verified theoretically and sufficient conditions for the two conclusions are given respectively.
Abstract: Prescribed-time Lag consensus, as a special case of prescribed-time cluster lag consensus, is first investigated. The task is to design a control protocol for each follower so that the multiagent system (MAS) achieves lag consensus in any specified time. To achieve this goal, we propose a new distributed controller, in which the control gains are designed as time-varying functions related to the pre-specified time. In addition, a state transformation is introduced to tackle the technical difficulty caused by time-varying functions of different powers in the theoretical proof process. Then, a solution for the cluster lag consensus problem of the MAS is provided, so that under the proposed control protocol, each subsystem composed of followers from the same group and the leader achieves lag consensus with a different lag time in the specified time. By using a state transformation, Graph theory and generalized Lyapunov stability theory, the validity of the designed schemes is verified theoretically and sufficient conditions for the two conclusions are given respectively. Finally, we give two simulation examples to show performances of the proposed solutions.