1,403 research outputs found
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
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
A Supermodular Optimization Framework for Leader Selection under Link Noise in Linear Multi-Agent Systems
In many applications of multi-agent systems (MAS), a set of leader agents
acts as a control input to the remaining follower agents. In this paper, we
introduce an analytical approach to selecting leader agents in order to
minimize the total mean-square error of the follower agent states from their
desired value in steady-state in the presence of noisy communication links. We
show that the problem of choosing leaders in order to minimize this error can
be solved using supermodular optimization techniques, leading to efficient
algorithms that are within a provable bound of the optimum. We formulate two
leader selection problems within our framework, namely the problem of choosing
a fixed number of leaders to minimize the error, as well as the problem of
choosing the minimum number of leaders to achieve a tolerated level of error.
We study both leader selection criteria for different scenarios, including MAS
with static topologies, topologies experiencing random link or node failures,
switching topologies, and topologies that vary arbitrarily in time due to node
mobility. In addition to providing provable bounds for all these cases,
simulation results demonstrate that our approach outperforms other leader
selection methods, such as node degree-based and random selection methods, and
provides comparable performance to current state of the art algorithms
Structure-Based Self-Triggered Consensus in Networks of Multiagents with Switching Topologies
In this paper, we propose a new self-triggered consensus algorithm in
networks of multi-agents. Different from existing works, which are based on the
observation of states, here, each agent determines its next update time based
on its coupling structure. Both centralized and distributed approaches of the
algorithms have been discussed. By transforming the algorithm to a proper
discrete-time systems without self delays, we established a new analysis
framework to prove the convergence of the algorithm. Then we extended the
algorithm to networks with switching topologies, especially stochastically
switching topologies. Compared to existing works, our algorithm is easier to
understand and implement. It explicitly provides positive lower and upper
bounds for the update time interval of each agent based on its coupling
structure, which can also be independently adjusted by each agent according to
its own situation. Our work reveals that the event/self triggered algorithms
are essentially discrete and more suitable to a discrete analysis framework.
Numerical simulations are also provided to illustrate the theoretical results
Non-Fragility and Partial Controllability of Multi-Agent Systems
Controllability of multi-agent systems is determined by the interconnection
topologies. In practice, losing agents can change the topologies of multi-agent
systems, which may affect the controllability. This paper studies non-fragility
of controllability influenced by losing agents. In virtue of the concept of
cutsets, necessary and sufficient conditions are established from a graphic
perspective, for strong non-fragility and weak non-fragility of
controllability, respectively. For multi-agent systems which contain important
agents, partial controllability is proposed in terms of the concept of
controllable node groups, and necessary and sufficient criteria are established
for partial controllability. Moreover, partial controllability preserving
problem is proposed. Utilizing the concept of compressed graphs, this problem
is transformed into finding the the minimal
vertex cutsets of the interconnection graph, which has a polynomial-time
complexity algorithm for the solution. Several constructive examples illuminate
the theoretical results
Distributed Consensus of Linear Multi-Agent Systems with Switching Directed Topologies
This paper addresses the distributed consensus problem for a linear
multi-agent system with switching directed communication topologies. By
appropriately introducing a linear transformation, the consensus problem is
equivalently converted to a stabilization problem for a class of switched
linear systems. Some sufficient consensus conditions are then derived by using
tools from the matrix theory and stability analysis of switched systems. It is
proved that consensus in such a multi-agent system can be ensured if each agent
is stabilizable and each possible directed topology contains a directed
spanning tree. Finally, a numerical simulation is given for illustration.Comment: The paper will be presented at the 2014 Australian Control Conference
(AUCC 2014), Canberra, Australi
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
Experimental Evaluation of Continuum Deformation with a Five Quadrotor Team
This paper experimentally evaluates continuum deformation cooperative control
for the first time. Theoretical results are expanded to place a bounding
triangle on the leader-follower system such that the team is contained despite
nontrivial tracking error. Flight tests were conducted with custom quadrotors
running a modified version of ArduPilot on a BeagleBone Blue in M-Air, an
outdoor netted flight facility. Motion capture and an onboard inertial
measurement unit were used for state estimation. Position error was
characterized in single vehicle tests using quintic spline trajectories and
different reference velocities. Five-quadrotor leader trajectories were
generated, and followers executed the continuum deformation control law
in-flight. Flight tests successfully demonstrated continuum deformation; future
work in characterizing error propagation from leaders to followers is
discussed
Almost Decouplability of any Directed Weighted Network Topology
This paper introduces a conception that any weighted directed network
topology is almost decouplable, which can help to transform the topology into a
similar form being composed of uncoupled vertices, and thus reduce the
complexity of analysis for networked dynamical systems. As an example of its
application, the consensus problem of linear multi-agent systems with
time-varying network topologies is addressed. As a result, a necessary and
sufficient condition for uniform consensus is proposed
Event-Triggered Control for Consensus of Multi-Agent Systems with Nonlinear Output and Directed Topologies
We propose a distributed event-triggered control law to solve the consensus
problem for multi-agent systems with nonlinear output. Under the condition that
the underlying digraph is strongly connected, we propose some sufficient
conditions related to the nonlinear output function and initial states to
guarantee that the event-triggered controller realizes consensus. Then the
results are extended to the case where the underlying directed graph contains a
directed spanning tree. These theoretical results are illustrated by numerical
simulations.Comment: arXiv admin note: text overlap with arXiv:1704.0542
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