ST-CBS: Spatio-Temporal Conflict Based Search in Continuous Space for Multi-Agent Pathfinding

초록

In this paper, we consider the problem of Multi-Agent Pathfinding (MAPF) in continuous space to find conflict-free paths. The difficulty of the problem arises from two primary factors. First, the involvement of multiple agents leads to combinatorial decision-making, escalating the search space exponentially. Second, the continuous space presents potentially infinite states and actions. To address these challenges, we propose a two-level approach, Spatio-Temporal Conflict Based Search (ST-CBS). For the low level, we develop Unidirectional Spatio-Temporal RRT* to generate a path in a spatio-temporal state space for each agent without considering inter-agent conflicts. At the high level, ST-CBS performs a best-first search on a constraints tree to resolve conflicts found in the paths of agents. Our method offers benefits in terms of deadlock prevention and faster computation. In the experiment, ST-CBS achieves higher success rates even with a large number of agents (100% for 20 or more agents) and faster planning and execution time compared to recent MAPF algorithms.

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