Exploiting constraints during prioritized path planning for teams of mobile robots

Coordinating the motion of multiple mobile robots is one of the fundamental problems in robotics. The predominant algorithms for coordinating teams of robots are decoupled and prioritized, thereby avoiding combinatorially hard planning problems typically faced by centralized approaches. We present a method for finding solvable priority schemes for such prioritized and decoupled planning techniques. Existing approaches apply a single priority scheme which makes them overly prone to failure in cases where valid solutions exists. By searching in the space of priorization schemes, our approach overcomes this limitation. To focus the search, our algorithm is guided by constraints generated from the task specification. To illustrate the appropriateness of this approach, the paper discusses experimental results obtained with real robots and through systematic robot simulation. The experimental results demonstrate that our approach successfully solves many more coordination problems than previous decoupled and prioritized techniques.