1,995 research outputs found
Connectivity-Preserving Coordination Control of Multi-Agent Systems with Time-Varying Delays
This paper presents a distributed position synchronization strategy that also
preserves the initial communication links for single-integrator multi-agent
systems with time-varying delays. The strategy employs a coordinating
proportional control derived from a specific type of potential energy,
augmented with damping injected through a dynamic filter. The injected damping
maintains all agents within the communication distances of their neighbours,
and asymptotically stabilizes the multi-agent system, in the presence of time
delays. Regarding the closed-loop single-integrator multi-agent system as a
double-integrator system suggests an extension of the proposed strategy to
connectivity-preserving coordination of Euler-Lagrange networks with
time-varying delays. Lyapunov stability analysis and simulation results
validate the two designs
Multi-Agent Distributed Coordination Control: Developments and Directions
In this paper, the recent developments on distributed coordination control,
especially the consensus and formation control, are summarized with the graph
theory playing a central role, in order to present a cohesive overview of the
multi-agent distributed coordination control, together with brief reviews of
some closely related issues including rendezvous/alignment, swarming/flocking
and containment control.In terms of the consensus problem, the recent results
on consensus for the agents with different dynamics from first-order,
second-order to high-order linear and nonlinear dynamics, under different
communication conditions, such as cases with/without switching communication
topology and varying time-delays, are reviewed, in which the algebraic graph
theory is very useful in the protocol designs, stability proofs and converging
analysis. In terms of the formation control problem, after reviewing the
results of the algebraic graph theory employed in the formation control, we
mainly pay attention to the developments of the rigid and persistent graphs.
With the notions of rigidity and persistence, the formation transformation,
splitting and reconstruction can be completed, and consequently the range-based
formation control laws are designed with the least required information in
order to maintain a formation rigid/persistent. Afterwards, the recent results
on rendezvous/alignment, swarming/flocking and containment control, which are
very closely related to consensus and formation control, are briefly
introduced, in order to present an integrated view of the graph theory used in
the coordination control problem. Finally, towards the practical applications,
some directions possibly deserving investigation in coordination control are
raised as well.Comment: 28 pages, 8 figure
Containment Control of Second-order Multi-agent Systems Under Directed Graphs and Communication Constraints
The distributed coordination problem of multi-agent systems is addressed in
this paper under the assumption of intermittent communication between agents in
the presence of time-varying communication delays. Specifically, we consider
the containment control problem of second-order multi-agent systems with
multiple dynamic leaders under a directed interconnection graph topology. Also,
communication between agents is performed only at some discrete instants of
time in the presence of irregular communication delays and packet dropout.
First, we present distributed control algorithms for double integrator dynamics
in the full and partial state feedback cases. Then, we propose a method to
extend our results to second-order systems with locally Lipschitz nonlinear
dynamics. In both cases, we show that the proposed approach leads to our
control objectives under sufficient conditions relating the characteristics of
the communication process and the control gains. We also show that our approach
can be applied to solve various similar coordination problems in multi-agent
systems under the same communication constraints. The effectiveness of the
proposed control schemes is illustrated through some examples and numerical
simulations.Comment: Modified version. Paper submitted for publicatio
Event-Triggered Communication and Control of Networked Systems for Multi-Agent Consensus
This article provides an introduction to event-triggered coordination for
multi-agent average consensus. We provide a comprehensive account of the
motivations behind the use of event-triggered strategies for consensus, the
methods for algorithm synthesis, the technical challenges involved in
establishing desirable properties of the resulting implementations, and their
applications in distributed control. We pay special attention to the
assumptions on the capabilities of the network agents and the resulting
features of the algorithm execution, including the interconnection topology,
the evaluation of triggers, and the role of imperfect information.
The issues raised in our discussion transcend the specific consensus problem
and are indeed characteristic of cooperative algorithms for networked systems
that solve other coordination tasks. As our discussion progresses, we make
these connections clear, highlighting general challenges and tools to address
them widespread in the event-triggered control of networked systems
Decentralized Event-Triggered Consensus over Unreliable Communication Networks
This article studies distributed event-triggered consensus over unreliable
communication channels. Communication is unreliable in the sense that the
broadcast channel from one agent to its neighbors can drop the event-triggered
packets of information, where the transmitting agent is unaware that the packet
was not received and the receiving agents have no knowledge of the transmitted
packet. Additionally, packets that successfully arrive at their destination may
suffer from time-varying communication delays. In this paper, we consider
directed graphs, and we also relax the consistency on the packet dropouts and
the delays. Relaxing consistency means that the delays and dropouts for a
packet broadcast by one agent can be different for each receiving node. We show
that even under this challenging scenario, agents can reach consensus
asymptotically while reducing transmissions of measurements based on the
proposed event-triggered consensus protocol. In addition, positive inter-event
times are obtained which guarantee that Zeno behavior does not occur.Comment: 20 pages, 5 figure
Robustness Analysis of Asynchronous Sampled-Data Multi-Agent Networks With Time-Varying Delays
In this paper, we study the simultaneous stability problem of a finite number
of locally inter-connected linear subsystems under practical constraints,
including asynchronous and aperiodic sampling, time-varying delays, and
measurement errors. We establish a new Lyapunov-based stability result for such
a decentralized system. This system has a particular simple structure of
interconnections, but it captures some key characteristics of a large class of
intermediate models derived from the consensus analysis of multi-agent systems.
The stability result is applicable to the estimation of the maximum allowable
inter-sampling periods and time delays based on individual dynamics and
coupling structures in the scenarios of consensus control via asynchronous
sampling of relative states and asynchronous broadcasting of self-sampled
states respectively. The asynchrony of aperiodic sampling and the existence of
measurement errors allow the utilization of some kinds of quantizing devices,
such as Logarithmic quantizers, in the process of data sampling, and allow the
introduction of a period of dwell time after each update of state measurement
to eliminate the Zeno behavior of events in event-based control. The extension
in the case with input saturations and input delays is also discussed
Constrained Optimal Consensus in Multi-agent Systems with First and Second Order Dynamics
This paper fully studies distributed optimal consensus problem in
non-directed dynamical networks. We consider a group of networked agents that
are supposed to rendezvous at the optimal point of a collective convex
objective function. Each agent has no knowledge about the global objective
function and only has access to its own local objective function, which is a
portion of the global one, and states information of agents within its
neighborhood set. In this setup, all agents coordinate with their neighbors to
seek the consensus point that minimizes the networks global objective function.
In the current paper, we consider agents with single-integrator and
double-integrator dynamics. We further suppose that agents movements are
limited by some convex inequality constraints. In order to find the optimal
consensus point under the described scenario, we combine the interior-point
optimization algorithm with a consensus protocol and propose a distributed
control law. The associated convergence analysis based on Lyapunov stability
analysis is provided
A Review on Cooperative Adaptive Cruise Control (CACC) Systems: Architectures, Controls, and Applications
Connected and automated vehicles (CAVs) have the potential to address the
safety, mobility and sustainability issues of our current transportation
systems. Cooperative adaptive cruise control (CACC), for example, is one
promising technology to allow CAVs to be driven in a cooperative manner and
introduces system-wide benefits. In this paper, we review the progress achieved
by researchers worldwide regarding different aspects of CACC systems.
Literature of CACC system architectures are reviewed, which explain how this
system works from a higher level. Different control methodologies and their
related issues are reviewed to introduce CACC systems from a lower level.
Applications of CACC technology are demonstrated with detailed literature,
which draw an overall landscape of CACC, point out current opportunities and
challenges, and anticipate its development in the near future
Periodic Event-Triggered Synchronization of Linear Multi-agent Systems with Communication Delays
Multi-agent systems cooperation to achieve global goals is usually limited by
sensing, actuation, and communication issues. At the local level, continuous
measurement and actuation is only approximated by the use of digital mechanisms
that measure and process information in order to compute and update new control
input values at discrete time instants. Interaction with other agents or
subsystems takes place, in general, through a digital communication channel
with limited bandwidth where transmission of continuous-time signals is not
possible. Additionally, communication channels may be subject to other
imperfections such as time-varying delays. This paper considers the problem of
consensus (or synchronization of state trajectories) of multi-agent systems
that are described by general linear dynamics and are connected using
undirected graphs. An event-triggered consensus protocol is proposed, where
each agent implements discretized and decoupled models of the states of its
neighbors. This approach not only avoids the need for continuous communication
between agents but also provides a decentralized method for transmission of
information in the presence of time-varying communication delays where each
agent decides its own broadcasting time instants based only on local
information. This method gives more flexibility for scheduling information
broadcasting compared to periodic and sampled-data implementations. The use of
discretized models by each agent allows for a periodic event-triggered strategy
where continuous actuation and continuous measurement of the states are not
necessary.Comment: 35 pages, 7 figures, A shorter version of this document was submitted
to the IEEE Transactions on Automatic Contro
Fixed-time consensus of multiple double-integrator systems under directed topologies: A motion-planning approach
This paper investigates the fixed-time consensus problem under directed
topologies. By using a motion-planning approach, a class of distributed
fixed-time algorithms are developed for a multi-agent system with
double-integrator dynamics. In the context of the fixed-time consensus, we
focus on both directed fixed and switching topologies. Under the directed fixed
topology, a novel class of distributed algorithms are designed, which guarantee
the consensus of the multi-agent system with a fixed settling time if the
topology has a directed spanning tree. Under the directed periodically
switching topologies, the fixedtime consensus is solved via the proposed
algorithms if the topologies jointly have a directed spanning tree. In
particular, the fixed settling time can be off-line pre-assigned according to
task requirements. Compared with the existing results, to our best knowledge,
it is the first time to solve the fixed-time consensus problem for
double-integrator systems under directed topologies. Finally, a numerical
example is given to illustrate the effectiveness of the analytical results
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