Emergency broadcasting strategies for distributed robotic groups under limited communication

Abstract

Execution of large-scale search and survey operations by groups of autonomous mobile robots requires the ability to respond to unforeseen events of different nature in a quick and efficient manner. In order to achieve this requirement, the available information about recent changes should be spread among all active group members as soon as possible. Informing a non-stationary group of mobile robots distributed across different regions of the operational area is a nontrivial task for large groups with limited communication capabilities. The paper addresses the problem of agent-based information distribution throughout a network in a new original formulation. In essence, the problem is to define an effective order of transferring data between single robots in order to achieve the fastest way of sharing it among the whole group. A number of heuristic strategies are proposed for building initial solutions alongside with the local search scheme for their further optimization. The comparison between the suggested approaches is made regarding both the solution quality and the speed of algorithm operation. Some issues related to the test instances generation are also considered.

Self-adaptive coordination for fuel-constrained robot teams with periodic and aperiodic communications

“…This work expands our previous papers 7,8,39 by presenting more strict communication requirements and more sophisticated efficiency criteria along with the additional EA mechanisms for the mission planning approach; and by the development of the continuous-time formulation of the broadcasting problem with a weighted graph and heterogeneous robotic group. New temporal-distance metrics are also introduced to match with the expanded problem statement.…”

“…As unaware team members differ by speed, are non-stationary and time-dependent (even though their future positions can be predicted), it lays an additional layer of complexity to the group routing problem. 8 Let the graph G = (V, E) represents the whole operational area of the mission, which is partitioned into a set of m connected locations represented by the graph vertices v i , i = 0, …, m. Each location here is associated with either a single mission task or a group of closely-spaced tasks, except for v 0 which stands for the rendezvous location. Each edge (v i , v j ) represents the existing path segment between two adjacent locations v i and v j and e ij > 0 is its length value.…”

“…Knowing the initial routes R 1 , R 2 , …R η of the whole group, the originator a χ has to determine if it is possible to distribute the new information among the group before the end of the operating period t τ < t O + O. In order to do this, the originator should solve the broadcasting problem 8 by finding the solution in the following form X = {a i (t)}, i = 1, …, η, t 2 T O such that:…”

“…The upper level is responsible for the global team coordination concerning both refuelling and communication needs, 7 while the lower level focuses on the network routing with an accent on the emergent behaviour. 8 The team rendezvous concept is the core of the approach as it binds two levels together to provide both periodic and aperiodic (event-driven) communication.…”

“…The following problem statement is an extension of a simple abstract group broadcasting model suggested in our previous papers. 8,39 In this work, we propose its continuous-time variation with a weighted graph and speed-heterogeneous agent group.…”