Uncertain Local Leader Selection in Distributed Formations

Leader-Follower is a hierarchical form of multi-robot formation control, where each robot aims to maintain specific predefined angle and distance from one or more robots in the team (referred to as its local leaders), while a single robot is selected to lead the entire formation to a desired destination. When the robots are given a specific formation to maintain, their goal is usually to minimize the deviation from this desired formation (maximizing the accuracy) during their journey. Previous work has considered optimality in an uncertain environment only in centralized setting (or using perfect, or almost perfect communication). In this paper we examine the problem of optimal multi-robot formation control in a distributed setting, while accounting for two challenges: sensory uncertainty and absence of communication. Specifically, we present an algorithm that allows each individual robot to estimate the overall formation accuracy of the other robots in their field of view via a tree reconstruction algorithm. The algorithm is used to select the most accurate local leader, or to generate virtual local leader via a weighted average of all visible robots. We provide both theoretical analysis and an extensive empirical evaluation (in ROS/Gazebo simulated environment) showing the effectiveness of the two approaches.