495 research outputs found
Optimal Pursuit of Moving Targets using Dynamic Voronoi Diagrams
(c) 2010 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.We consider Voronoi-like partitions for a team of moving targets distributed in the plane, such that each set in
this partition is uniquely associated with a particular moving
target in the following sense: a pursuer residing inside a given
set of the partition can intercept this moving target faster than any other pursuer outside this set. It is assumed that each
moving target employs its own "evading" strategy in response
to the pursuer actions. In contrast to standard formulations of
problems of this kind in the literature, the evading strategy
does necessarily restrict the evader to be slower than its
pursuer. In the special case when all moving targets employ
a uniform evading strategy, the previous problem reduces to
the characterization of the Zermelo-Voronoi diagram
Optimal steering for kinematic vehicles with applications to spatially distributed agents
The recent technological advances in the field of autonomous vehicles have resulted in a growing impetus for researchers to improve the current framework of mission planning and execution within both the military and civilian contexts. Many recent efforts towards this direction emphasize the importance of replacing the so-called monolithic paradigm, where a mission is planned, monitored, and controlled by a unique global decision maker, with a network centric paradigm, where the same mission related tasks are performed by networks of interacting decision makers (autonomous vehicles). The interest in applications involving teams of autonomous vehicles is expected to significantly grow in the near future as new paradigms for their use are constantly being proposed for a diverse spectrum of real world applications.
One promising approach to extend available techniques for addressing problems involving a single autonomous vehicle to those involving teams of autonomous vehicles is to use the concept of Voronoi diagram as a means for reducing the complexity of the multi-vehicle problem. In particular, the Voronoi diagram provides a spatial partition of the environment the team of vehicles operate in, where each element of this partition is associated with a unique vehicle from the team. The partition induces, in turn, a graph abstraction of the operating space that is in a one-to-one correspondence with the network abstraction of the team of autonomous vehicles; a fact that can provide both conceptual and analytical advantages during mission planning and execution. In this dissertation, we propose the use of a new class of Voronoi-like partitioning schemes with respect to state-dependent proximity (pseudo-) metrics rather than the Euclidean distance or other generalized distance functions, which are typically used in the literature. An important nuance here is that, in contrast to the Euclidean distance, state-dependent metrics can succinctly capture system theoretic features of each vehicle from the team (e.g., vehicle kinematics), as well as the environment-vehicle interactions, which are induced, for example, by local winds/currents. We subsequently illustrate how the proposed concept of state-dependent Voronoi-like partition can induce local control schemes for problems involving networks of spatially distributed autonomous vehicles by examining different application scenarios.PhDCommittee Chair: Tsiotras Panagiotis; Committee Member: Egerstedt Magnus; Committee Member: Feron Eric; Committee Member: Haddad Wassim; Committee Member: Shamma Jef
Active Target Defense Differential Game with a Fast Defender
This paper addresses the active target defense differential game where an
Attacker missile pursues a Target aircraft. A Defender missile is fired by the
Target's wingman in order to intercept the Attacker before it reaches the
aircraft. Thus, a team is formed by the Target and the Defender which cooperate
to maximize the distance between the Target aircraft and the point where the
Attacker missile is intercepted by the Defender missile, while the Attacker
tries to minimize said distance. The results shown here extend previous work.
We consider here the case where the Defender is faster than the Attacker. The
solution to this differential game provides optimal heading angles for the
Target and the Defender team to maximize the terminal separation between Target
and Attacker and it also provides the optimal heading angle for the Attacker to
minimize the said distance.Comment: 9 pages, 8 figures. A shorter version of this paper will be presented
at the 2015 American Control Conferenc
Escape Regions of the Active Target Defense Differential Game
The active target defense differential game is addressed in this paper. In
this differential game an Attacker missile pursues a Target aircraft. The
aircraft is however aided by a Defender missile launched by, say, the wingman,
to intercept the Attacker before it reaches the Target aircraft. Thus, a team
is formed by the Target and the Defender which cooperate to maximize the
separation between the Target aircraft and the point where the Attacker missile
is intercepted by the Defender missile, while the Attacker simultaneously tries
to minimize said distance. This paper focuses on characterizing the set of
coordinates such that if the Target's initial position belong to this set then
its survival is guaranteed if both the Target and the Defender follow their
optimal strategies. Such optimal strategies are presented in this paper as
well.Comment: 19 pages, 9 figures. arXiv admin note: text overlap with
arXiv:1502.0274
Stability of a class of multi-agent tracking systems with unstable subsystems
In this work, we pre-deploy a large number of
smart agents to monitor an area of interest. This area could
be divided into many Voronoi cells by using the knowledge of
Voronoi diagram and every Voronoi site agent is responsible
for monitoring and tracking the target in its cell. Then, a
cooperative relay tracking strategy is proposed such that during
the tracking process, when a target enters a new Voronoi cell,
this event triggers the switching of both tracking agents and
communication topology. This is significantly different from the
traditional switching topologies. In addition, during the tracking
process, the topology and tracking agents switch, which may lead
the tracking system to be stable or unstable. The system switches
either among consecutive stable subsystems and consecutive
unstable subsystems or between stable and unstable subsystems.
The objective of this paper is to design a tracking strategy
guaranteeing overall successful tracking despite the existence of
unstable subsystems. We also address extended discussions on the
case where the dynamics of agents are subject to disturbances
and the disturbance attenuation level is achieved. Finally, the
proposed tracking strategy is verified by a set of simulations
Capturing an Evader Using Multiple Pursuers with Sensing Limitations in Convex Environment
A modified continuous-time pursuit-evasion game with multiple pursuers and a single evader is studied. The game has been played in an obstacle-free convex environment which consists an exit gate through which the evader may escape. The geometry of the convex is unknown to all players except pursuers know the location of the exit gate and they can communicate with each other. All players have equal maximum velocities and identical sensing range. An evader is navigating inside the environment and seeking the exit gate to win the game. A novel sweep-pursuit-capture strategy for the pursuers to search and capture the evader under some necessary and sufficient conditions is presented. We also show that three pursuers are sufficient to finish the operation successfully. Non-holonomic wheeled mobile robots of the same configurations have been used as the pursuers and the evader. Simulation studies demonstrate the performance of the proposed strategy in terms of interception time and the distance traveled by the players.
Analysis of multi-agent systems under varying degrees of trust, cooperation, and competition
Multi-agent systems rely heavily on coordination and cooperation to achieve a variety of tasks. It is often assumed that these agents will be fully cooperative, or have reliable and equal performance among group members. Instead, we consider cooperation as a spectrum of possible interactions, ranging from performance variations within the group to adversarial agents. This thesis examines several scenarios where cooperation and performance are not guaranteed. Potential applications include sensor coverage, emergency response, wildlife management, tracking, and surveillance. We use geometric methods, such as Voronoi tessellations, for design insight and Lyapunov-based stability theory to analyze our proposed controllers. Performance is verified through simulations and experiments on a variety of ground and aerial robotic platforms. First, we consider the problem of Voronoi-based coverage control, where a group of robots must spread out over an environment to provide coverage. Our approach adapts online to sensing and actuation performance variations with the group. The robots have no prior knowledge of their relative performance, and in a distributed fashion, compensate by assigning weaker robots a smaller portion of the environment. Next, we consider the problem of multi-agent herding, akin to shepherding. Here, a group of dog-like robots must drive a herd of non-cooperative sheep-like agents around the environment. Our key insight in designing the control laws for the herders is to enforce geometrical relationships that allow for the combined system dynamics to reduce to a single nonholonomic vehicle. We also investigate the cooperative pursuit of an evader by a group of quadrotors in an environment with no-fly zones. While the pursuers cannot enter the no-fly zones, the evader moves freely through the zones to avoid capture. Using tools for Voronoi-based coverage control, we provide an algorithm to distribute the pursuers around the zone's boundary and minimize capture time once the evader emerges. Finally, we present an algorithm for the guaranteed capture of multiple evaders by one or more pursuers in a bounded, convex environment. The pursuers utilize properties of the evader's Voronoi cell to choose a control strategy that minimizes the safe-reachable area of the evader, which in turn leads to the evader's capture
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