Frontier-led swarming: Robust multi-robot coverage of unknown environments

Abstract

This paper proposes a novel swarm-based control algorithm for exploration and coverage of unknown environments, while maintaining a formation that permits short-range communication. The algorithm combines two elements: swarm rules for maintaining a close-knit formation and frontier search for driving exploration and coverage. Inspired by natural systems in which large numbers of simple agents (e.g., schooling fish, flocking birds, swarming insects) perform complicated collective behaviors for efficiency and safety, the first element uses three simple rules to maintain a swarm formation. The second element provides a means to select promising regions to explore (and cover) by minimising a cost function involving robots’ relative distance to frontier cells and the frontier’s size. We tested the performance of our approach on heterogeneous and homogeneous groups of mobile robots in different environments. We measure both coverage performance and swarm formation statistics as indicators of the robots’ ability to explore effectively while maintaining a formation conducive to short-range communication. Through a series of comparison experiments, we demonstrate that our proposed strategy has superior performance to recently presented map coverage methodologies and conventional swarming methods. • A novel, distributed algorithm leveraging the strengths of frontier-based area coverage and swarm behaviors is proposed for large-scale multi-robot systems. • Each robot can directly exchange the individual coverage and obstacle information with a set of neighbors without passing through a central station. • An improved artificial potential field obstacle avoidance method is designed based on Lidar information. • System robustness and fault tolerance of the proposed strategy is validated and analysed through a series of real experiments. • This paper demonstrates our space coverage controller’s relative merits with respect to the frontierbased map coverage strategy without swarming, and the three different map coverage control laws through a rigorous comparative study. • Algorithms are examined on both homogeneous and heterogeneous robot teams within a shortranged communication. Hence, the proposed system can normally work in unknown and uncertain environments.