Voronoi diagrams—a survey of a fundamental geometric data structure
ACM Computing Surveys (CSUR)
Distributed Anonymous Mobile Robots: Formation of Geometric Patterns
SIAM Journal on Computing
Self-stabilization
Coordination without communication: the case of the flocking problem
Discrete Applied Mathematics - Fun with algorithms 2 (FUN 2001)
Fault-Tolerant Flocking in a k-Bounded Asynchronous System
OPODIS '08 Proceedings of the 12th International Conference on Principles of Distributed Systems
Fault-Tolerant Flocking of Mobile Robots with Whole Formation Rotation
AINA '09 Proceedings of the 2009 International Conference on Advanced Information Networking and Applications
Stabilizing flocking via leader election in robot networks
SSS'07 Proceedings of the 9h international conference on Stabilization, safety, and security of distributed systems
On detecting termination in the crash-recovery model
Euro-Par'07 Proceedings of the 13th international Euro-Par conference on Parallel Processing
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This paper considers a system of autonomous mobile robots that can move freely in a two-dimensional plane, and where a number of them can fail by crashing. The crash of a robot can be either permanent or temporary, that is, after its crash the robot either executes no action or it recovers from its failure. These robots repeatedly go through a succession of activation cycles during which they observe the environment, compute a destination and move. In particular, we assume weak robots, in the sense that robots cannot communicate explicitly between each other. Also, they cannot remember their past computations (i.e., oblivious). Finally, robots do not agree on a common coordinate system. In this paper, we address a fault-tolerant flocking problem under the crash-recovery model. That is, starting from any initial configuration, a group of non-faulty robots are required to form a desired pattern, and move together while following a robot leader on a given trajectory, and keeping such a pattern in movement. Specifically, we propose a fault-tolerant flocking algorithm in the semi-synchronous model that allows correct robots to dynamically form a regular polygon in finite time, and maintain it in movement infinitely often. Our algorithm relies on the existence of two devices, namely an eventually perfect failure detector oracle to ensure failure detection, and an eventual leader oracle to handle leader election. The algorithm tolerates permanent crash failures, and also crash recovery failures of robots due to its oblivious feature. The proposed algorithm ensures the necessary restrictions on the movement of robots in order to avoid collisions between them. In addition, it is self-stabilizing.