14,347 research outputs found
Distributed Observers Design for Leader-Following Control of Multi-Agent Networks (Extended Version)
This paper is concerned with a leader-follower problem for a multi-agent
system with a switching interconnection topology. Distributed observers are
designed for the second-order follower-agents, under the common assumption that
the velocity of the active leader cannot be measured in real time. Some dynamic
neighbor-based rules, consisting of distributed controllers and observers for
the autonomous agents, are developed to keep updating the information of the
leader. With the help of an explicitly constructed common Lyapunov function
(CLF), it is proved that each agent can follow the active leader. Moreover, the
tracking error is estimated even in a noisy environment. Finally, a numerical
example is given for illustration.Comment: Automatica 200
A New Encounter Between Leader-Follower Tracking and Observer-Based Control: Towards Enhancing Robustness against Disturbances
This paper studies robust tracking control for a leader-follower multi-agent
system (MAS) subject to disturbances. A challenging problem is considered here,
which differs from those in the literature in two aspects. First, we consider
the case when all the leader and follower agents are affected by disturbances,
while the existing studies assume only the followers to suffer disturbances.
Second, we assume the disturbances to be bounded only in rates of change rather
than magnitude as in the literature. To address this new problem, we propose a
novel observer-based distributed tracking control design. As a distinguishing
feature, the followers can cooperatively estimate the disturbance affecting the
leader to adjust their maneuvers accordingly, which is enabled by the design of
the first-of-its-kind distributed disturbance observers. We build specific
tracking control approaches for both first- and second-order MASs and prove
that they can lead to bounded-error tracking, despite the challenges due to the
relaxed assumptions about disturbances. We further perform simulation to
validate the proposed approaches
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 unified framework of fully distributed adaptive output time-varying formation control for linear multi-agent systems: an observer viewpoint
This paper presents a unified framework of time-varying formation (TVF)
design for general linear multi-agent systems (MAS) based on an observer
viewpoint from undirected to directed topology, from stabilization to tracking
and from a leader without input to a one with bounded input. The followers can
form a TVF shape which is specified by piecewise continuously differential
vectors. The leader's trajectory, which is available to only a subset of
followers, is also time-varying. For the undirected formation tracking and
directed formation stabilization cases, only the relative output measurements
of neighbors are required to design control protocols; for the directed
formation tracking case, the agents need to be introspective (i.e. agents have
partial knowledge of their own states) and the output measurements are
required. Furthermore, considering the real applications, the leader with
bounded input case is studied. One main contribution of this paper is that
fully distributed adaptive output protocols, which require no global
information of communication topology and do not need the absolute or relative
state information, are proposed to solve the TVF control problem. Numerical
simulations including an application to nonholonomic mobile vehicles are
provided to verify the theoretical results.Comment: 21 page
Guaranteed Cost Tracking for Uncertain Coupled Multi-agent Systems Using Consensus over a Directed Graph
This paper considers the leader-follower control problem for a linear
multi-agent system with directed communication topology and linear nonidentical
uncertain coupling subject to integral quadratic constraints (IQCs). A
consensus-type control protocol is proposed based on each agent's states
relative to its neighbors and leader's state relative to agents which observe
the leader. A sufficient condition is obtained by overbounding the cost
function. Based on this sufficient condition, a computational algorithm is
introduced to minimize the proposed guaranteed bound on tracking performance,
which yields a suboptimal bound on the system consensus control and tracking
performance. The effectiveness of the proposed method is demonstrated using a
simulation example.Comment: Accepted for presentation at the 2013 Australian Control conferenc
Fault Tolerant Control for Networked Mobile Robots
Teams of networked autonomous agents have been used in a number of
applications, such as mobile sensor networks and intelligent transportation
systems. However, in such systems, the effect of faults and errors in one or
more of the sub-systems can easily spread throughout the network, quickly
degrading the performance of the entire system. In consensus-driven dynamics,
the effects of faults are particularly relevant because of the presence of
unconstrained rigid modes in the transfer function of the system. Here, we
propose a two-stage technique for the identification and accommodation of a
biased-measurements agent, in a network of mobile robots with time invariant
interaction topology. We assume these interactions to only take place in the
form of relative position measurements. A fault identification filter deployed
on a single observer agent is used to estimate a single fault occurring
anywhere in the network. Once the fault is detected, an optimal leader-based
accommodation strategy is initiated. Results are presented by means of
numerical simulations and robot experiments.Comment: 7 pages, 7 figures, conferenc
Similarity Decomposition Approach to Oscillatory Synchronization for Multiple Mechanical Systems With a Virtual Leader
This paper addresses the oscillatory synchronization problem for multiple
uncertain mechanical systems with a virtual leader, and the interaction
topology among them is assumed to contain a directed spanning tree. We propose
an adaptive control scheme to achieve the goal of oscillatory synchronization.
Using the similarity decomposition approach, we show that the position and
velocity synchronization errors between each mechanical system (or follower)
and the virtual leader converge to zero. The performance of the proposed
adaptive scheme is shown by numerical simulation results.Comment: 15 pages, 3 figures, published in 2014 Chinese Control Conferenc
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
Consensus tracking in multi agent system with nonlinear and non identical dynamics via event driven sliding modes
In this work, leader follower consensus objective has been addressed with the
synthesis of an event based controller utilizing sliding mode robust control.
The schema has been partitioned into two parts viz. finite time consensus
problem and event triggered control mechanism. A nonlinear multi agent system
with non identical dynamics has been put forward to illustrate the robust
capabilities of the proposed control. The first part incorporates matching of
states of the followers with those of the leader via consensus tracking
algorithm. In the subsequent part, an event triggered rule is devised to save
computational power and restrict periodic updating of the controller involved
while ensuring desired closed loop performance of the system. Switching of the
event based controller is achieved via sliding mode control. Advantage of using
switched controller like sliding mode is that it retains its inherent
robustness as well as event triggering approach aids in saving energy
expenditure. Efficacy of the proposed scheme is confirmed via numerical
simulations.Comment: preprint, "IEEE Transactions on Automatic Control
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
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