1,720,986 research outputs found
On the consensus and bipartite consensus in high-order multi-agent dynamical systems with antagonistic interactions
No full textThe aim of this paper is to address consensus and bipartite consensus for a group of
homogeneous agents, under the assumption that their mutual interactions can be described
by a weighted, signed, connected and structurally balanced communication graph. This
amounts to assuming that the agents can be split into two antagonistic groups such that
interactions between agents belonging to the same group are cooperative, and hence represented by nonnegative weights, while interactions between agents belonging to opposite
groups are antagonistic, and hence represented by nonpositive weights. In this framework,
bipartite consensus can always be reached under the stabilizability assumption on the
state-space model describing the dynamics of each agent. On the other hand, (nontrivial)
standard consensus may be achieved only under very demanding requirements, both on
the Laplacian associated with the communication graph and on the agents' description.
In particular, consensus may be achieved only if there is a sort of "equilibrium" between
the two groups, both in terms of cardinality and in terms of the weights of the "conflicting
interactions" amongst agents
On the Stabilizability and Consensus of Positive Homogeneous Multi-Agent Dynamical Systems
No full textIn this note we consider a supervisory control
scheme that achieves either asymptotic stability or consensus for
a group of homogenous agents described by a positive state-space
model. Each agent is modeled by means of the same SISO positive
state-space model, and the supervisory controller, representing
the information exchange among the agents, is implemented via
a static output feedback. Necessary and sufficient conditions for
the asymptotic stability, or the consensus of all agents, are derived
under the positivity constraint
Preliminary results on the controllability and stabilizability of non-homogeneous multi-agent dynamical systems
No full textAbstract—In this paper we consider a supervisory control
scheme for non-homogenous multi-agent systems. Each agent
is modeled through an independent strictly proper SISO state
space model, and the supervisory controller, representing the
information exchange among the agents, is implemented in turn
via a linear state-space model. Controllability and observability
of the overall system are characterized, and some preliminary
results about stability and stabilizability are provided. The
paper extends to non-homogenous multi-agent systems some
of the results obtained in [2], [3], [5] for the homogenous case
On the bipartite consensus of higher-order multi-agent systems with antagonistic interactions and switching topologies
No full textIn this paper we, investigate the bipartite consensus of higher-order multiagent
systems, by assuming that the interactions among agents are either cooperative
or antagonistic and that the communication graph switches among a finite number
of possible configurations.We first show that the “lifting approach”, proposed in [3]
to model opinion dynamics in case of antagonistic interactions and agents modeled
as integrators, can be extended to the case of higher order multi-agent systems with
cooperative/antagonistic interactions and switching topologies. Subsequently,we are
able to translate the bipartite consensus problem into a consensus problem among
cooperative agents with switching topologies. This allows us to make use of the
results obtained in [13] and hence to solve the bipartite consensus problem
Asymptotic Tracking of Non Sinusoidal Periodic References: a Switched Linear Internal Model Approach
No full textThe regulation theory is a very robust way to achieve the asymptotic tracking of input references on Linear Time-Invariant systems generated by an exosystem. Nevertheless, the classical regulation theory cannot be applied to the asymptotic tracking of non-sinusoidal periodic references having an infinite number of harmonics (as triangular waves). In literature many methods have been proposed to deal with this kind of problem. In this paper a novel approach based on a Switched Linear Internal Model is proposed by presenting some preliminary results. This approach seems particularly promising in terms of robustness to disturbances not “captured” by the internal model and this is the main motivation of starting this study
A fault tolerant architecture for supervisory control of discrete event systems
No full textIn this paper the problem of Fault Tolerant Control (FTC) in the framework of Discrete Event Systems (DES) modeled as automata is considered. The approach we follow is the so-called active approach in which the supervisor actively reacts to the detection of a malfunctioning component in order to eventually meet degraded control specifications. Starting from an appropriate model of the system, we recall the notion of safe diagnosability as a necessary step in order to achieve fault tolerant supervision of DES. We then introduce two new notions: (i) "safe controllability", which represents the capability, after the occurrence of a fault, of steering the system away from forbidden zones and (ii) "active fault tolerant system", which is the property of safely continuing operation after faults. We show how it is possible to define a general control architecture to deal with the FTC problem by introducing a special
kind of automaton, called a "diagnosing-controller"
Hierarchical Control Architectures in Industrial Automation: a Design Approach based on the Generalized Actuator Concept
No full textIn this paper an effective design approach to the design of hierarchical control architectures for the automation industrial plants is presented. The main characteristic of the solution is the clear and structural separation between “policies” and “actions” deriving from the use of a novel abstract entity in modelling automation plants: the Generalized Actuator.
Particular attention is paid to illustrate how to define generalized actuators starting from a “bare plant”. The potentialities of this method are emphasized by means of a case study
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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