Complete visibility for robots with lights in O(1) time

Gokarna Sharma, Ramachandran Vaidyanathan, Jerry L. Trahan, Costas Busch, Suresh Rai

Research output: Chapter in Book/Report/Conference proceedingConference contribution

28 Scopus citations


We consider the problem of repositioning N autonomous robots on a plane so that each robot is visible to all others (the Complete Visibility problem); a robot cannot see another robot if its visibility is obstructed by a third robot positioned between them on a straight line. This problem is important since it provides a basis to solve many other problems under obstructed visibility. Robots operate following Look-Compute-Move (LCM) cycles and communicate with other robots using colored lights as in the recently proposed robots with lights model. The challenge posed by this model is that each robot has only a constant number of colors for its lights (symbols for communication) and no memory (except for the persistence of lights) between LCM cycles. Our goal is to minimize the number of rounds needed to solve Complete Visibility, where a round is measured as the time duration for all robots to execute at least one complete LCM cycle since the end of the previous round. The best previously known algorithm for Complete Visibility on this robot model has runtime of O(logN) rounds. That algorithm has the assumptions of full synchronicity, chirality, and robot paths may collide. In this paper we present the first algorithm for Complete Visibility with O(1) runtime that runs on the semi-synchronous (and also the fully synchronous) model. The proposed algorithm is deterministic, does not have the chirality assumption, and is collision free.

Original languageEnglish (US)
Title of host publicationStabilization, Safety, and Security of Distributed Systems - 18th International Symposium, SSS 2016, Proceedings
EditorsFranck Petit, Borzoo Bonakdarpour
PublisherSpringer Verlag
Number of pages19
ISBN (Print)9783319492582
StatePublished - 2016
Externally publishedYes
Event18th International Symposium on Stabilization, Safety, and Security of Distributed Systems, SSS 2016 - Lyon, France
Duration: Nov 7 2016Nov 10 2016

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume10083 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference18th International Symposium on Stabilization, Safety, and Security of Distributed Systems, SSS 2016

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science(all)


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