19,474 research outputs found
Cooperative Task Planning of Multi-Agent Systems Under Timed Temporal Specifications
In this paper the problem of cooperative task planning of multi-agent systems
when timed constraints are imposed to the system is investigated. We consider
timed constraints given by Metric Interval Temporal Logic (MITL). We propose a
method for automatic control synthesis in a two-stage systematic procedure.
With this method we guarantee that all the agents satisfy their own individual
task specifications as well as that the team satisfies a team global task
specification.Comment: Submitted to American Control Conference 201
Towards Swarm Calculus: Urn Models of Collective Decisions and Universal Properties of Swarm Performance
Methods of general applicability are searched for in swarm intelligence with
the aim of gaining new insights about natural swarms and to develop design
methodologies for artificial swarms. An ideal solution could be a `swarm
calculus' that allows to calculate key features of swarms such as expected
swarm performance and robustness based on only a few parameters. To work
towards this ideal, one needs to find methods and models with high degrees of
generality. In this paper, we report two models that might be examples of
exceptional generality. First, an abstract model is presented that describes
swarm performance depending on swarm density based on the dichotomy between
cooperation and interference. Typical swarm experiments are given as examples
to show how the model fits to several different results. Second, we give an
abstract model of collective decision making that is inspired by urn models.
The effects of positive feedback probability, that is increasing over time in a
decision making system, are understood by the help of a parameter that controls
the feedback based on the swarm's current consensus. Several applicable
methods, such as the description as Markov process, calculation of splitting
probabilities, mean first passage times, and measurements of positive feedback,
are discussed and applications to artificial and natural swarms are reported
COORDINATION OF LEADER-FOLLOWER MULTI-AGENT SYSTEM WITH TIME-VARYING OBJECTIVE FUNCTION
This thesis aims to introduce a new framework for the distributed control of multi-agent systems with adjustable swarm control objectives. Our goal is twofold: 1) to provide an overview to how time-varying objectives in the control of autonomous systems may be applied to the distributed control of multi-agent systems with variable autonomy level, and 2) to introduce a framework to incorporate the proposed concept to fundamental swarm behaviors such as aggregation and leader tracking. Leader-follower multi-agent systems are considered in this study, and a general form of time-dependent artificial potential function is proposed to describe the varying objectives of the system in the case of complete information exchange. Using Lyapunov methods, the stability and boundedness of the agents\u27 trajectories under single order and higher order dynamics are analyzed. Illustrative numerical simulations are presented to demonstrate the validity of our results. Then, we extend these results for multi-agent systems with limited information exchange and switching communication topology. The first steps of the realization of an experimental framework have been made with the ultimate goal of verifying the simulation results in practice
Synchronization in dynamical networks of locally coupled self-propelled oscillators
Systems of mobile physical entities exchanging information with their
neighborhood can be found in many different situations. The understanding of
their emergent cooperative behaviour has become an important issue across
disciplines, requiring a general conceptual framework in order to harvest the
potential of these systems. We study the synchronization of coupled oscillators
in time-evolving networks defined by the positions of self-propelled agents
interacting in real space. In order to understand the impact of mobility in the
synchronization process on general grounds, we introduce a simple model of
self-propelled hard disks performing persistent random walks in 2 space and
carrying an internal Kuramoto phase oscillator. For non-interacting particles,
self-propulsion accelerates synchronization. The competition between agent
mobility and excluded volume interactions gives rise to a richer scenario,
leading to an optimal self-propulsion speed. We identify two extreme dynamic
regimes where synchronization can be understood from theoretical
considerations. A systematic analysis of our model quantifies the departure
from the latter ideal situations and characterizes the different mechanisms
leading the evolution of the system. We show that the synchronization of
locally coupled mobile oscillators generically proceeds through coarsening
verifying dynamic scaling and sharing strong similarities with the phase
ordering dynamics of the 2 XY model following a quench. Our results shed
light into the generic mechanisms leading the synchronization of mobile agents,
providing a efficient way to understand more complex or specific situations
involving time-dependent networks where synchronization, mobility and excluded
volume are at play
Optimal strategies for driving a mobile agent in a guidance by repulsion model
We present a guidance by repulsion model based on a driver-evader interaction
where the driver, assumed to be faster than the evader, follows the evader but
cannot be arbitrarily close to it, and the evader tries to move away from the
driver beyond a short distance. The key ingredient allowing the driver to guide
the evader is that the driver is able to display a circumvention maneuver
around the evader, in such a way that the trajectory of the evader is modified
in the direction of the repulsion that the driver exerts on the evader. The
evader can thus be driven towards any given target or along a sufficiently
smooth path by controlling a single discrete parameter acting on driver's
behavior. The control parameter serves both to activate/deactivate the
circumvention mode and to select the clockwise/counterclockwise direction of
the circumvention maneuver. Assuming that the circumvention mode is more
expensive than the pursuit mode, and that the activation of the circumvention
mode has a high cost, we formulate an optimal control problem for the optimal
strategy to drive the evader to a given target. By means of numerical shooting
methods, we find the optimal open-loop control which reduces the number of
activations of the circumvention mode to one and which minimizes the time spent
in the active~mode. Our numerical simulations show that the system is highly
sensitive to small variations of the control function, and that the cost
function has a nonlinear regime which contributes to the complexity of the
behavior of the system, so that a general open-loop control would not be of
practical interest. We then propose a feedback control law that corrects from
deviations while preventing from an excesive use of the circumvention mode,
finding numerically that the feedback law significantly reduces the cost
obtained with the open-loop control
Refining self-propelled particle models for collective behaviour
Swarming, schooling, flocking and herding are all names given to the wide variety of collective behaviours exhibited by groups of animals, bacteria and even individual cells. More generally, the term swarming describes the behaviour of an aggregate of agents (not necessarily biological) of similar size and shape which exhibit some emergent property such as directed migration or group cohesion. In this paper we review various individual-based models of collective behaviour and discuss their merits and drawbacks. We further analyse some one-dimensional models in the context of locust swarming. In specific models, in both one and two dimensions, we demonstrate how varying the parameters relating to how much attention individuals pay to their neighbours can dramatically change the behaviour of the group. We also introduce leader individuals to these models with the ability to guide the swarm to a greater or lesser degree as we vary the parameters of the model. We consider evolutionary scenarios for models with leaders in which individuals are allowed to evolve the degree of influence neighbouring individuals have on their subsequent motion
Discrete modes of social information processing predict individual behavior of fish in a group
Individual computations and social interactions underlying collective
behavior in groups of animals are of great ethological, behavioral, and
theoretical interest. While complex individual behaviors have successfully been
parsed into small dictionaries of stereotyped behavioral modes, studies of
collective behavior largely ignored these findings; instead, their focus was on
inferring single, mode-independent social interaction rules that reproduced
macroscopic and often qualitative features of group behavior. Here we bring
these two approaches together to predict individual swimming patterns of adult
zebrafish in a group. We show that fish alternate between an active mode in
which they are sensitive to the swimming patterns of conspecifics, and a
passive mode where they ignore them. Using a model that accounts for these two
modes explicitly, we predict behaviors of individual fish with high accuracy,
outperforming previous approaches that assumed a single continuous computation
by individuals and simple metric or topological weighing of neighbors behavior.
At the group level, switching between active and passive modes is uncorrelated
among fish, yet correlated directional swimming behavior still emerges. Our
quantitative approach for studying complex, multi-modal individual behavior
jointly with emergent group behavior is readily extensible to additional
behavioral modes and their neural correlates, as well as to other species
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