Conflict-Free Route Planning in Dynamic Environments

Motion planning for multiple robots is tractable in case we can assume a roadmap on which all the robots travel, which is often the case in many automated guided vehicle domains, such as factory floors or container terminals. We present an O (nv log(nv) + n(2)v) (n the number of nodes, v the number of vehicles) route planning algorithm for a single robot, which can find the minimum-time route given a set of existing route plans that it may not interfere with. In addition, we present an algorithm that can propagate delay through the plans of the robots in case one or more robots are delayed. This delay-propagation algorithm allows us to implement a Pareto-optimal plan repair scheme, in which one robot can improve its route plan without adversely affecting the other robots. We compare this approach to several plan repair schemes from the literature, which are based on the idea of giving a higher priority to non-delayed agents.