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74
SwarmBot: a New Distributed Robotic Concept
 AUTONOMOUS ROBOTS
, 2003
"... The swarm intelligence paradigm has proven to have very interesting properties such as robustness, flexibility and ability to solve complex problems exploiting parallelism and selforganization. Several robotics implementations of this paradigm confirm that these properties can be exploited for the ..."
Abstract

Cited by 126 (70 self)
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The swarm intelligence paradigm has proven to have very interesting properties such as robustness, flexibility and ability to solve complex problems exploiting parallelism and selforganization. Several robotics implementations of this paradigm confirm that these properties can be exploited for the control of a population of physically independent mobile robots. The work
Faulttolerant gathering algorithms for autonomous mobile robots
 SIAM J. Comput
, 2004
"... This paper studies fault tolerant algorithms for the problem of gathering N autonomous mobile robots. A gathering algorithm, executed independently by each robot, must ensure that all robots are gathered at one point within nite time. In a failureprone system, a gathering algorithm is required to ..."
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Cited by 53 (4 self)
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This paper studies fault tolerant algorithms for the problem of gathering N autonomous mobile robots. A gathering algorithm, executed independently by each robot, must ensure that all robots are gathered at one point within nite time. In a failureprone system, a gathering algorithm is required to successfully gather the nonfaulty robots, independently of the behavior of the faulty ones. Both crash and Byzantine faults are considered. It is rst observed that most existing algorithms fail to operate correctly in a setting allowing crash failures. Subsequently, an algorithm tolerant against one crashfaulty robot in a system of three or more robots is presented. It is then observed that all known algorithms fail to operate correctly in a system prone to Byzantine faults, even in the presence of a single fault. Moreover, it is shown that in an asynchronous environment it is impossible to perform a successful gathering in a 3robot system, even if at most one of them might fail in a Byzantine manner. Thus, the problem is studied in a fully synchronous system. An algorithm is provided in this model for gathering N 3 robots with at most a single faulty robot, and a more general gathering algorithm is given in an Nrobot system with up to f faults, where N 3f +1.
Solving the robots gathering problem
 Proc. 30th International Colloquium on Automata, Languages and Programming (ICALP 2003), LNCS 2719
, 2003
"... Abstract. Consider a set of n> 2 simple autonomous mobile robots (decentralized, asynchronous, no common coordinate system, no identities, no central coordination, no direct communication, no memory of the past, deterministic) moving freely in the plane and able to sense the positions of the othe ..."
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Cited by 43 (6 self)
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Abstract. Consider a set of n> 2 simple autonomous mobile robots (decentralized, asynchronous, no common coordinate system, no identities, no central coordination, no direct communication, no memory of the past, deterministic) moving freely in the plane and able to sense the positions of the other robots. We study the primitive task of gathering them at a point not fixed in advance (Gathering Problem). In the literature, most contributions are simulationvalidated heuristics. The existing algorithmic contributions for such robots are limited to solutions for n ≤ 4 or for restricted sets of initial configurations of the robots. In this paper, we present the first algorithm that solves the Gathering Problem for any initial configuration of the robots. 1
Gathering of asynchronous robots with limited visibility
 Theoretical Computer Science
, 2005
"... In this paper we study the problem of gathering in the same location of the plane a collection of identical oblivious mobile robots. Previous investigations have focused mostly on the unlimited visibility setting, where each robot can always see all the other ones, regardless of their distance. In t ..."
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Cited by 41 (4 self)
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In this paper we study the problem of gathering in the same location of the plane a collection of identical oblivious mobile robots. Previous investigations have focused mostly on the unlimited visibility setting, where each robot can always see all the other ones, regardless of their distance. In the more difficult and realistic setting where the robots have limited visibility, the existing algorithmic results are only for convergence (towards a common point, without ever reaching it) and only for synchronous environments, where robots’ movements are assumed to be performed instantaneously. In contrast, we study this problem in a totally asynchronous setting, where robots ’ actions, computations, and movements require a finite but otherwise unpredictable amount of time. We present a protocol that allows anonymous oblivious robots with limited visibility to gather in the same location in finite time, provided they have orientation (i.e., agreement on a coordinate system). Our result indicates that, with respect to gathering, orientation is at least as powerful as instantaneous movements.
Gathering asynchronous oblivious mobile robots in a ring
 Proc. 17th International Symposium on Algorithms and Computation (ISAAC
, 2006
"... Gathering asynchronous oblivious mobile robots in a ring ∗ ..."
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Cited by 38 (8 self)
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Gathering asynchronous oblivious mobile robots in a ring ∗
Gathering Autonomous Mobile Robots
 In Proc. SIROCCO
, 2002
"... We study the problem of coordinating a set of autonomous mobile robots that can freely move in a twodimensional plane; in particular, we want them to gather at a point not fixed in advance (GATHERING PROBLEM). We introduce a model of weak robots (decentralized, asynchronous, no common knowledge, no ..."
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Cited by 35 (6 self)
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We study the problem of coordinating a set of autonomous mobile robots that can freely move in a twodimensional plane; in particular, we want them to gather at a point not fixed in advance (GATHERING PROBLEM). We introduce a model of weak robots (decentralized, asynchronous, no common knowledge, no identities, no central coordination, no direct communication, oblivious) which can observe the set of all points in the plane which are occupied by other robots. Based on this observation, a robot uses a deterministic algorithm to compute a destination, and moves there. We prove that these robots are too weak to gather at a point in finite time. Therefore, we strengthen them with the ability to detect whether more than one robot is at a point (multiplicity). We analyze the GATHERING PROBLEM for these stronger robots. We show that the problem is still unsolvable if there are only two robots in the system. For 3 and 4 robots, we give algorithms that solve the GATHERING PROBLEM. For more than 4 robots, we present an algorithm that gathers the robots in finite time if they are not in a specific symmetric configuration at the beginning (biangular configuration). We show how to solve such initial configurations separately. However, the general solution of the GATHERING PROBLEM remains an open problem.
Algorithms for Rapidly Dispersing Robot Swarms in Unknown Environments
, 2002
"... We develop and analyze algorithms for dispersing a swarm of primitive robots in an unknown environment, R. The primary objective is to minimize the makespan, that is, the time to fill the entire region. An environment is composed of pixels that form a connected subset of the integer grid. There is a ..."
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Cited by 28 (6 self)
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We develop and analyze algorithms for dispersing a swarm of primitive robots in an unknown environment, R. The primary objective is to minimize the makespan, that is, the time to fill the entire region. An environment is composed of pixels that form a connected subset of the integer grid. There is at most one robot per pixel and robots move horizontally or vertically at unit speed. Robots enter R by means of k &ge; 1 door pixels. Robots are primitive finite automata, only having local communication, local sensors, and a constantsized memory. We first give algorithms for the singledoor case...
Coordination without Communication: The Case of the Flocking Problem
 Discrete Applied Mathematics
, 2003
"... In this paper, we study the distributed coordination and control of a set of asynchronous, anonymous, memoryless mobile vehicles that can freely move on a twodimensional plane but cannot communicate among themselves. In particular, we analyze the problem of forming a certain pattern and following a ..."
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Cited by 20 (3 self)
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In this paper, we study the distributed coordination and control of a set of asynchronous, anonymous, memoryless mobile vehicles that can freely move on a twodimensional plane but cannot communicate among themselves. In particular, we analyze the problem of forming a certain pattern and following a designated vehicle, referred to as the leader, while maintaining the pattern: the ocking problem.
Circle formation of weak mobile robots
, 2006
"... The contribution is twofold. We first show the validity of the conjecture of Défago and Konagaya in [DK02], i.e., there exists no deterministic oblivious algorithm solving the Uniform Transformation Problem for any number of robots ∗. Next, a protocol which solves deterministically the Circle Format ..."
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Cited by 13 (7 self)
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The contribution is twofold. We first show the validity of the conjecture of Défago and Konagaya in [DK02], i.e., there exists no deterministic oblivious algorithm solving the Uniform Transformation Problem for any number of robots ∗. Next, a protocol which solves deterministically the Circle Formation Problem in finite time for any number n of weak robots—n / ∈ {4, 6, 8}—is proposed. The robots are assumed to be uniform, anonymous, oblivious, and they share no kind of coordinate system nor common sense of direction.
Arbitrary Pattern Formation by Asynchronous, Anonymous, Oblivious Robots
, 2008
"... From an engineering point of view, the problem of coordinating a set of autonomous, mobile robots for the purpose of cooperatively performing a task has been studied extensively over the past decade. In contrast, in this paper we aim at an understanding of the fundamental algorithmic limitations on ..."
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Cited by 13 (5 self)
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From an engineering point of view, the problem of coordinating a set of autonomous, mobile robots for the purpose of cooperatively performing a task has been studied extensively over the past decade. In contrast, in this paper we aim at an understanding of the fundamental algorithmic limitations on what a set of autonomous mobile robots can or cannot achieve. We therefore study a hard task for a set of weak robots. The task is for the robots in the plane to form any arbitrary pattern that is given in advance. This task is fundamental in the sense that if the robots can form any pattern, they can agree on their respective roles in a subsequent, coordinated action. The robots are weak in several aspects. They are anonymous; they cannot explicitly communicate with each other, but only observe the positions of the others; they cannot remember the past; they operate in a very strong form of asynchronicity. We show that the tasks that such a system of robots can perform depend strongly on their common agreement about their environment, i.e., the readings of their environment sensors. If the robots have no common agreement about their environment, they cannot form an arbitrary pattern. If each robot has a compass needle that indicates North (the robot world is a flat surface, and compass needles are parallel), then any odd number of robots can form an arbitrary pattern, but an even number cannot (in the worst case). If each robot has two independent compass needles, say North and East, then any set of robots can form any pattern.