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  • Coordinated exploration of labyrinthine environments with application to the pursuit-evasion problemLeibniz LaboratoryMagma teamDamien Pellier Humbert Fiorino{Pellier, Fiorino}@imag.fr

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    Plan Problems tackled Principle of surveillance algorithms A cooperative approach Discussion and future prospects Demonstration

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    Problems tackledpursuit evasion problem for mobile robots by a multi robot cooperation approachDistributed decisionSharing robots knowledgeComputing motion strategiesDeliberation protocol

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    Principle of surveillance algorithmsBuild a motion strategy that guarantees an intruder will be discovered by the pursuers [Suzuki 92]Constraints on the environment known [Yamashita 00] unknown [Rajko 01]Constraints on the robot perception omnidirectional perception [Lavalle 97] flash light perception [Simov 01]Limits complexity management of robots resources

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    A cooperative approach PrincipleAlgorithm for one pursuer Assumptions- the environment is known- the robots have an infinite omnidirectional perception- the intruder can have an infinite speed >> robots speed

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    A cooperative approachConstruction of the trajectory 1st step : the critical points must be found (a critical point is an obstacle vertex that has an internal angle < 180) 2nd step: from the critical vertices list, build the visibility graph of the environment

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    A cooperative approachConstruction of the trajectory 3td step: the surveillance graph construction gathers all surveillance trajectories in the environment

    Example from the critical point 1: 4th step: choice of the best motion strategy based upon the Dijkstra algorithm so as to compute the shortest surveillance pathN: ClearedC: Contaminated

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    A cooperative approachCooperation implementation Detection of the delegation points Assistance computation The stuck robot tries to split the environment that can be monitored by independent robots

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    A cooperative approach Cooperation implementation Tasks delegation: the deliberation protocol A robot can play 4 different roles: Explorer Guard Idle robot Stuck robot The robots role changes during the exploration The deliberation protocol is based on contracts between the team robots

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    A cooperative approach Cooperation implementation Deliberation protocol

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    A cooperative approach Discussion and future prospects Number of robots minimization by making them work as a team Deliberation protocol allows an efficient use of the robots resources Computation distribution Limitation of the critical points representation Adaptation of the deliberation protocol for unknown environments

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    Demonstration