Priority Evacuation from a Disk Using Mobile Robots

TL;DR

This paper studies a new robot search problem where multiple robots start from the center of a disk to evacuate a queen robot through a hidden exit on the perimeter, providing bounds on the evacuation time.

Contribution

It introduces a novel search problem with multiple robots, offering algorithms and bounds for the queen's evacuation time on a disk.

Findings

Proposed an evacuation algorithm with guaranteed time bounds.

Established lower bounds on evacuation time for the queen.

Demonstrated the effectiveness of multiple robots in evacuation scenarios.

Abstract

We introduce and study a new search-type problem with ($n+1$)-robots on a disk. The searchers (robots) all start from the center of the disk, have unit speed, and can communicate wirelessly. The goal is for a distinguished robot (the queen) to reach and evacuate from an exit that is hidden on the perimeter of the disk in as little time as possible. The remaining $n$ robots (servants) are there to facilitate the queen's objective and are not required to reach the hidden exit. We provide upper and lower bounds for the time required to evacuate the queen from a unit disk. Namely, we propose an algorithm specifying the trajectories of the robots which guarantees evacuation of the queen in time always better than $2 + 4(\sqrt{2}-1) \frac{\pi}{n}$ for $n \geq 4$ servants. We also demonstrate that for $n \geq 4$ servants the queen cannot be evacuated in time less than $2+\frac{\pi}{n}+\frac{2}{n^2}$.