Following Leaders in Byzantine Multirobot Systems by Using Blockchain Technology

Eduardo Castello Ferrer,Jose Luis Lopez-Presa,Ernesto Jimenez,Javier Martin-Rueda

doi:10.1109/tro.2021.3104243

Eduardo Castello Ferrer, Jose Luis Lopez-Presa + Show 2 more

Open Access

https://doi.org/10.1109/tro.2021.3104243

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Abstract

Interest in multirobot systems is rising rapidly both in academia and in industry. The use of multiple robots working in a coordinated way, rather than a single robot, has several advantages in a diverse range of applications. However, few studies have focused on operations in which robots can behave maliciously and alter the outcome of the collective mission. In this article, we present a set of Byzantine Follow The Leader (BFTL) problems, in which a subset of robots in the system shows unintended or inconsistent behavior (i.e., Byzantine robots). In the BFTL problems, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">leaders</i> discover routes from their starting positions to specific destinations and guide the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">followers</i> , while <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Byzantine</i> robots try to hinder the leaders and mislead the followers. In this research, blockchain technology is used as a communication tool within multirobot systems, for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">leaders</i> to broadcast directions to the whole group. We propose algorithms to tackle the BFTL problems, prove their correctness, and validate them in simulated experiments of realistic scenarios. Results show that the proposed algorithms mitigate the impact of Byzantine robots in multirobot systems conducting a BFTL mission. Our analysis provides minimum and maximum boundary calculations for important metrics including number of robots reaching their destination, number of steps taken, and weight requirements of the chain used during the mission. Our results provide a path toward the deployment of byzantine-resistant real-world multirobot systems.

Highlights

M ULTIROBOT systems have several advantages over single robots in a diverse range of applications, such as environmental monitoring [11], exploration [5], and search and Manuscript received February 23, 2021; revised May 24, 2021; accepted August 4, 2021
We defined a family of Follow The Leader (FTL) problems in the presence of Byzantine robots, in which the destination was not known a priori
In a system with k leaders, each provided with t tokens, the maximum length of the chain would be kt blocks

Summary

Introduction

M ULTIROBOT systems have several advantages over single robots in a diverse range of applications, such as environmental monitoring [11], exploration [5], and search and Manuscript received February 23, 2021; revised May 24, 2021; accepted August 4, 2021. This paper was recommended for publication by Associate Editor F. These advantages typically include faster collective resolution of the targeted task [7], the ability to collectively interact with larger workspaces and objects [3], and less cost [32] because robots tend to be simpler. Multirobot systems can move bigger objects [31], clean larger surfaces [20], and gather scattered objects faster than a single powerful robot [48]

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