Decentralized Connectivity-Preserving Deployment of Large-Scale Robot Swarms

Abstract

We present a decentralized and scalable approach for deployment of a robot swarm. Our approach tackles scenarios in which the swarm must reach multiple spatially distributed targets, and enforce the constraint that the robot network cannot be split. The basic idea behind our work is to construct a logical tree topology over the physical network formed by the robots. The logical tree acts as a backbone used by robots to enforce connectivity constraints. We study and compare two algorithms to form the logical tree: outwards and inwards. These algorithms differ in the order in which the robots join the tree: the outwards algorithm starts at the tree root and grows towards the targets, while the inwards algorithm proceeds in the opposite manner. Both algorithms perform periodic reconfiguration, to prevent suboptimal topologies from halting the growth of the tree. Our contributions are (i) The formulation of the two algorithms; (ii) A comparison of the algorithms in extensive physics-based simulations; (iii) A validation of our findings through real-robot experiments. reach a number of distant locations. While navigating to these locations, the robots must spread without splitting the network topology in disconnected components. The robots must achieve a final configuration in which data can flow between any two target locations, using the robots as relays.It is important to notice that it is not required for all of the robots to take part in the final topology. Rather, it is desirable that as few robots as possible are engaged in connectivity maintenance, as this would free any extra robot for others tasks or to act as occasional replacement for damaged robot in the topology. In contrast, the robots that are part of the final topology must form a persistent communication backbone that can be used by any robot when necessary.

Multi-Robot Coordination Analysis, Taxonomy, Challenges and Future Scope

“…It is becoming a more and more relevant topic in the development of MRS. Many works explicitly address this significant issue in large scale MRS [83][84][85][86].…”

Swarm Relays: Distributed Self-Healing Ground-and-Air Connectivity Chains

“…There are two general approaches to connectivity maintenance in multi-robot systems: strict end-to-end connectivity [3], [4], or relaxed intermittent connectivity [5], [6], [7]. While the first demands to maintain a link from the source to the sinks (the ends of each branch of the network graph), the latter allows for momentary local breaks in the communication topology.…”

“…When the mission requires to continuously relay information, like video, operators commands or offloaded computation, strict end-to-end connectivity might be preferred; this is the approach we use in this work. Algebraic Connectivity The problem of preserving end-toend connectivity is widely discussed in recent literature [3], [4], [8]. Some works use continuous control models with algebraic connectivity [9] and implement mission-related control laws [10], considering robot failures.…”

Multi-Robot Persistent Surveillance With Connectivity Constraints

“…A tree growing algorithm [29] arranges the robots into a starlike topology to visit multiple task locations. Ponda et al [30] present an algorithm for allocation of data streaming and relaying tasks to maintain connectivity to a base station during task execution.…”