Search

In this article, the distributed nonlinear placement problem for a class of multicluster Euler–Lagrange systems is considered. The problem is first converted into a time-varying noncooperative game. A distributed Nash equilibrium seeking algorithm composed of an auxiliary double-integrator system and a coordinated-tracking observer is designed to solve the problem. The convergence results are established by an iterative approach and the small gain theorem. The effectiveness of the algorithm is demonstrated via simulations. [ABSTRACT FROM AUTHOR]

This article studies a fully distributed optimal coordinated control problem with the global cost function for networked Euler–Lagrange (EL) systems subject to unknown model parameters. In particular, the global cost function is the sum of all the local cost functions assigned to each agent and only available to itself. The objective is to minimize the global cost function in a distributed manner while achieving a consensus on its optimal solution. Since the model parameters of the considered EL systems are not available, a new auxiliary system is introduced as a reference model, and its outputs exponentially converge the optimal solution of the global cost function. A fully distributed optimal control algorithm without requiring global information is first proposed. Then, an alternative distributed optimal algorithm via the event-triggered mechanism is proposed to reduce the communication cost. In particular, by combining an edge-based adaptive gain method, the proposed event-triggered optimal algorithm is also fully distributed. Finally, numerical simulation is carried out to validate the theoretical results. [ABSTRACT FROM AUTHOR]

This article investigates the distributed localization and circumnavigation problem for a group of agents using bearing measurements. In particular, there is one agent appointed as a pathfinder in the group that is responsible for measuring the relative bearing with respect to an uncertain target. We consider both persistent and intermittent measurement cases. The objective is to drive all the agents such that they first localize the given target and then circumnavigate it isometrically. First, for the persistent measurement case, a distributed control algorithm is developed by introducing a distributed observer. In terms of Lyapunov theorem, it is shown that the proposed control algorithm guarantees the achievement of the localization and circumnavigation objective. Next, we focus on the case of the intermittent bearing measurement. In particular, another feasible distributed control algorithm is designed. Based on the nonlinear contraction theory, it is demonstrated that the localization and circumnavigation objective can also be achieved. Simulation and experiment results verify the effectiveness of the proposed distributed control algorithms. [ABSTRACT FROM AUTHOR]

This paper studies the cooperative set aggregation problem for second-order multiagent systems by utilizing the approximate projection algorithm. First, an aggregation law that uses the approximate projection is proposed, where the feasible set of the approximate projection points is established based on an Euclidean distance with respect to the targeted set and a deviated angle with respect to the exact projection point. Under the proposed law, the position vectors of all the agents are shown to reach an agreement in the intersection of their individual targeted sets and the velocity vector of each agent is shown to converge to zero. Then, a time-dependent performance bound is set for the norm of the weighted error of the relative positions among neighboring agents and the absolute velocity of the agent, and a performance-guaranteed aggregation controller is designed to guarantee the prescribed transient performance. During the process of aggregation, the norm of the weighted error is shown to not exceed the performance bound. The convergence conditions of the proposed algorithms with respect to the control strength and the terms induced by the approximate projection are obtained by using the techniques of convex analysis and Lyapunov stability. Simulations are provided to validate the theoretical results. [ABSTRACT FROM AUTHOR]

In this study, the distributed optimisation problem for linear multi‐agent systems with disturbance rejection is considered. The topology graph is assumed to be uniformly jointly strongly connected and the disturbance is not limited to satisfy the matching condition. Each agent is assigned with a local quadratic cost function and the objective is to minimise the sum of local cost functions based on information exchange. The authors propose a distributed observer for each agent such that other agents' cost functions are obtained. Then, the state feedback and output feedback optimal algorithms are designed based on the output of the distributed observer. The theoretical results are validated by simulations. [ABSTRACT FROM AUTHOR]

In this paper, the cooperative output regulation problem of nonlinear multi-agent system is studied. Both the cases of a linear exosystem and a nonlinear exosystem are considered. We focus on the situation of limited information exchange, i.e., only partial set of followers have access to the exosystem information and each follower exchanges the information with only its local neighbors. We first relax the classical manifold assumption on the regulator equations. In particular, the regulator equations are rebuilt and the zero-output manifold is provided not by the dynamics of the exosystem as given in the current literatures, but by exosystem signal and its higher-order derivatives. Then, a high-gain based distributed observer is designed to estimate the exosystem signal and its higher-order derivatives for the case of a linear exosystem. In the second place, a sliding-mode based distributed observer is proposed to estimate the exosystem signal and its higher-order derivatives for the case of a nonlinear exosystem. Based on the proposed distributed observers, nonlinear controllers are designed such that the cooperative output regulation is achieved with a global convergence property. Finally, simulations are provided to validate the theoretical results. [ABSTRACT FROM AUTHOR]

This paper studies the consensus problem for multi-agent systems. A distributed consensus algorithm is developed by constructing homogeneous pulse width modulators for agents in the network. In particular, a certain percentage of the sampling period named duty cycle is modulated according to some state difference with respect to the neighbors at each sampling instant. During each duty cycle, the amplitude of the pulse is fixed. The proposed pulse width modulation scheme enables all agents to sample asynchronously with arbitrarily large sampling periods. It provides an alternative digital implementation strategy for multi-agent systems. We show that consensus is achieved asymptotically under the proposed scheme. The results are compared with the self-triggered ternary controller. [ABSTRACT FROM AUTHOR]

This brief considers the existence of periodic behaviors for discrete-time second-order multiagent systems with input saturation constraints. We first consider the case where the agent dynamics is a double integrator and then establish conditions on the feedback gains of the linear consensus control law for achieving periodic behaviors. This, in turn, shows that the previously established sufficient condition for reaching global consensus has a necessary aspect since these two conditions are exclusive. We further consider all other second-order agent dynamics and show that these multiagent systems under the linear consensus law exhibit periodic solutions provided the feedback gains satisfy certain conditions. Simulation results are used to validate the theoretical findings. [ABSTRACT FROM PUBLISHER]

This brief considers the synchronization problem of coupled nonlinear dynamical systems over time-varying interaction graphs. We first show that infinite joint connectivity is necessary for achieving globally asymptotic synchronization. We then show that the commonly used Lipschitz condition on the nonlinear self-dynamics is not sufficient to ensure synchronization even for an arbitrarily large coupling strength. A sufficient synchronization condition is established in terms of the times of connectivity, the integral of the Lipschitz gain, and the network parameters. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we consider the global consensus problem for discrete-time multi-agent systems with input saturation constraints under fixed undirected topologies. We first give necessary conditions for achieving global consensus via a distributed protocol based on relative state measurements of the agent itself and its neighboring agents. We then focus on two special cases, where the agent model is either neutrally stable or a double integrator. For the neutrally stable case, any linear protocol of a particular form, which solves the consensus problem for the case without input saturation constraints, also solves the global consensus problem for the case with input saturation constraints. For the double integrator case, we show that a subset of linear protocols, which solve the consensus problem for the case without saturation constraints, also solve the global consensus problem for the case with input saturation constraints. The results are illustrated by numerical simulations. [Copyright &y& Elsevier]

This brief studies distributed containment control for double-integrator dynamics in the presence of both stationary and dynamic leaders. In the case of stationary leaders, we propose a distributed containment control algorithm and study conditions on the network topology and the control gains to guarantee asymptotic containment control in any dimensional space. In the case of dynamic leaders, we study two cases: leaders with an identical velocity and leaders with nonidentical velocities. For the first case, we propose two distributed containment control algorithms to solve, respectively, asymptotic containment control under a switching directed network topology and finite-time containment control under a fixed directed network topology. In particular, asymptotic containment control can be achieved for any dimensional space if the network topology is fixed and for only the 1-D space if the network topology is switching. For the second case, we propose a distributed containment control algorithm under a fixed network topology where the communication patterns among the followers are undirected and derive conditions on the network topology and the control gains to guarantee asymptotic containment control for any dimensional space. Both simulation results and experimental results on a multi-robot platform are provided to validate some theoretical results. [ABSTRACT FROM AUTHOR]