SPACE: Swarm Pheromone Fields for Adaptive Collision-Aware Exploration
For swarm robotics researchers, SPACE demonstrates that coordination primarily improves safety rather than coverage time in congested environments, addressing the safety-efficiency tradeoff.
SPACE uses a shared pheromone field to coordinate large robot swarms (up to 256 robots) in exploration, achieving 4-17x fewer inter-robot contacts than a greedy planner while maintaining coverage time within 2% of the near-optimal planner.
Massive robot swarms can explore unknown environments quickly, but adding robots eventually stops helping. Doorways and dense traffic create congestion, increasing inter-robot contacts and reducing the value of each additional robot. We study this safety-efficiency tradeoff for ground swarms of tens to hundreds of robots. We present SPACE, Swarm Pheromone Fields for Adaptive Collision-Aware Exploration. Inspired by ant foraging, SPACE maintains a shared environmental field with an attractive frontier pheromone, a repellent explore pheromone, and a fast robot-density field. Coordination is decentralized and mediated through this field. We evaluate SPACE on real building floorplans, namely sixteen home layouts from the HouseExpo dataset and eight campus floors from the KTH dataset, with swarms of up to two hundred and fifty-six robots. SPACE lies on the empirical Pareto frontier. It attains the lowest inter-robot contact rate at every congested swarm size, four to seventeen times fewer than a greedy nearest-frontier planner, while keeping coverage time within about two percent of that near time-optimal planner. The results indicate that, at this scale, coordination mainly improves safety rather than coverage time.