16,820 research outputs found
Coordination of Multi-Agent Systems under Switching Topologies via Disturbance Observer Based Approach
In this paper, a leader-following coordination problem of heterogeneous
multi-agent systems is considered under switching topologies where each agent
is subject to some local (unbounded) disturbances. While these unknown
disturbances may disrupt the performance of agents, a disturbance observer
based approach is employed to estimate and reject them. Varying communication
topologies are also taken into consideration, and their byproduct difficulties
are overcome by using common Lyapunov function techniques. According to the
available information in difference cases, two disturbance observer based
protocols are proposed to solve this problem. Their effectiveness is verified
by simulations.Comment: 12 pages, 4 figures, 2 table
Robust Consensus Tracking of Heterogeneous Multi-Agent Systems under Switching Topologies
In this paper, we consider a robust consensus tracking problem of
heterogeneous multi-agent systems with time-varying interconnection topologies.
Based on common Lyapunov function and internal model techniques, both state and
output feedback control laws are derived to solve this problem. The proposed
design is robust by admitting some parameter uncertainties in the multi-agent
system.Comment: 11 pages, 4 figures, accepte
Coordinated Output Regulation of Heterogeneous Linear Systems under Switching Topologies
This paper constructs a framework to describe and study the coordinated
output regulation problem for multiple heterogeneous linear systems. Each agent
is modeled as a general linear multiple-input multiple-output system with an
autonomous exosystem which represents the individual offset from the group
reference for the agent. The multi-agent system as a whole has a group
exogenous state which represents the tracking reference for the whole group.
Under the constraints that the group exogenous output is only locally available
to each agent and that the agents have only access to their neighbors'
information, we propose observer-based feedback controllers to solve the
coordinated output regulation problem using output feedback information. A
high-gain approach is used and the information interactions are allowed to be
switched over a finite set of fixed networks containing both graphs that have a
directed spanning tree and graphs that do not. The fundamental relationship
between the information interactions, the dwell time, the non-identical
dynamics of different agents, and the high-gain parameters is given.
Simulations are shown to validate the theoretical results
Cooperative Control of Linear Multi-Agent Systems via Distributed Output Regulation and Transient Synchronization
A wide range of multi-agent coordination problems including reference
tracking and disturbance rejection requirements can be formulated as a
cooperative output regulation problem. The general framework captures typical
problems such as output synchronization, leader-follower synchronization, and
many more. In the present paper, we propose a novel distributed regulator for
groups of identical and non-identical linear agents. We consider global
external signals affecting all agents and local external signals affecting only
individual agents in the group. Both signal types may contain references and
disturbances. Our main contribution is a novel coupling among the agents based
on their transient state components or estimates thereof in the output feedback
case. This coupling achieves transient synchronization in order to improve the
cooperative behavior of the group in transient phases and guarantee a desired
decay rate of the synchronization error. This leads to a cooperative reaction
of the group on local disturbances acting on individual agents. The
effectiveness of the proposed distributed regulator is illustrated by a vehicle
platooning example and a coordination example for a group of four non-identical
3-DoF helicopter models
Adaptive Leader-Following Consensus for a Class of Higher-Order Nonlinear Multi-Agent Systems with Directed Switching Networks
In this paper, we study the leader-following consensus problem for a class of
uncertain nonlinear multi-agent systems under jointly connected directed
switching networks. The uncertainty includes constant unbounded parameters and
external disturbances. We first extend the recent result on the adaptive
distributed observer from global asymptotical convergence to global exponential
convergence. Then, by integrating the conventional adaptive control technique
with the adaptive distributed observer, we present our solution by a
distributed adaptive state feedback control law. Our result is illustrated by
the leader-following consensus problem for a group of van der Pol oscillators.Comment: 21 pages, 5 figures. In this replacement version, the higher-order
case is considered instead of the second-order case. Also, the main
difference of this version from the reference [16] is that Appendix B is
added to show the existence of the limit of the function V(t) defined in the
equation (33) as t tends to infinit
Internal Model Approach to Cooperative Robust Output Regulation for Linear Uncertain Time-Delay Multi-Agent Systems
In this paper, we study the cooperative robust output regulation problem for
linear uncertain multi-agent systems with both communication delay and input
delay by the distributed internal model approach. The problem includes the
leader-following consensus problem of linear multi-agent systems with
time-delay as a special case. We first generalize the internal model design
method to systems with both communication delay and input delay. Then, under a
set of standard assumptions, we have obtained the solution of the problem via
both the state feedback control and the output feedback control. In contrast
with the existing results, our results apply to general uncertain linear
multi-agent systems, accommodate a large class of leader signals, and achieve
the asymptotic tracking and disturbance rejection at the same time.Comment: 15 pages, 3 figure
Cooperative Global Robust Stabilization for a Class of Nonlinear Multi-Agent Systems and its Application
This paper studies the cooperative global robust stabilization problem for a
class of nonlinear multi-agent systems. The problem is motivated from the study
of the cooperative global robust output regulation problem for the class of
nonlinear multi-agent systems in normal form with unity relative degree which
was studied recently under the conditions that the switching network is
undirected and some nonlinear functions satisfy certain growth condition. We
first solve the stabilization problem by using the multiple Lyapunov functions
approach and the average dwell time method. Then, we apply this result to the
cooperative global robust output regulation problem for the class of nonlinear
systems in normal form with unity relative degree under directed switching
network, and have removed the conditions that the switching network is
undirected and some nonlinear functions satisfy certain growth condition.Comment: 9 pages, 1 figure. This paper was submitted to the journal
"Automatica
Minimum-Rank Dynamic Output Consensus Design for Heterogeneous Nonlinear Multi-Agent Systems
In this paper, we propose a new and systematic design framework for output
consensus in heterogeneous Multi-Input Multi-Output (MIMO) general nonlinear
Multi-Agent Systems (MASs) subjected to directed communication topology. First,
the input-output feedback linearization method is utilized assuming that the
internal dynamics is Input-to-State Stable (ISS) to obtain linearized
subsystems of agents. Consequently, we propose local dynamic controllers for
agents such that the linearized subsystems have an identical closed-loop
dynamics which has a single pole at the origin whereas other poles are on the
open left half complex plane. This allows us to deal with distinct agents
having arbitrarily vector relative degrees and to derive rank- cooperative
control inputs for those homogeneous linearized dynamics which results in a
minimum rank distributed dynamic consensus controller for the initial nonlinear
MAS. Moreover, we prove that the coupling strength in the consensus protocol
can be arbitrarily small but positive and hence our consensus design is
non-conservative. Next, our design approach is further strengthened by tackling
the problem of randomly switching communication topologies among agents where
we relax the assumption on the balance of each switched graph and derive a
distributed rank- dynamic consensus controller. Lastly, a numerical example
is introduced to illustrate the effectiveness of our proposed framework.Comment: Revised version submitted to IEEE Transactions on Control of Network
System
Input-Feedforward-Passivity-Based Distributed Optimization Over Jointly Connected Balanced Digraphs
In this paper, a distributed optimization problem is investigated via input
feedforward passivity. First, an input-feedforward-passivity-based
continuous-time distributed algorithm is proposed. It is shown that the error
system of the proposed algorithm can be decomposed into a group of individual
input feedforward passive (IFP) systems that interact with each other using
output feedback information. Based on this IFP framework, convergence
conditions of a suitable coupling gain are derived over weight-balanced and
uniformly jointly strongly connected (UJSC) topologies. It is also shown that
the IFP-based algorithm converges exponentially when the topology is strongly
connected. Second, a novel distributed derivative feedback algorithm is
proposed based on the passivation of IFP systems. While most works on directed
topologies require knowledge of eigenvalues of the graph Laplacian, the
derivative feedback algorithm is fully distributed, namely, it is robust
against randomly changing weight-balanced digraphs with any positive coupling
gain and without knowing any global information. Finally, numerical examples
are presented to illustrate the proposed distributed algorithms.Comment: 15 pages, 9 figures, accepted by IEEE Transactions on Automatic
Contro
Delayed state synchronization of continuous-time multi-agent systems in the presence of unknown communication delays (including complete proofs)
This paper studies delayed synchronization of continuous-time multi-agent
systems (MAS) in the presence of unknown nonuniform communication delays. A
delay-free transformation is developed based on a communication network which
is a directed spanning tree, which can transform the original MAS to a new one
without delays. By using this transformation, we design a static protocol for
full-state coupling and a dynamic protocol for delayed state synchronization
for homogeneous MAS via full- and partial-state coupling. Meanwhile, the
delayed output synchronization is also studied for heterogeneous MAS, which is
achieved by using a low-gain and output regulation based dynamic protocol
design via the delay-free transformation.Comment: Accepted by the 31th CCDC held by Nanchang, China, June 3rd-5th, 201
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