Incorporating Potential Contingency Tasks in Multi-Robot Mission Planning

Abstract

In most complex missions, unexpected situations arise that may interfere with the planned execution of mission tasks. These situations result in the generation of contingency tasks that need to be executed before the originally planned tasks are completed. Potential contingency tasks may not always affect mission tasks due to the inherent uncertainty in the environment. Deferring action on a potential contingency task may incur a penalty in terms of wasted time due to idle robots if the contingency task becomes a bottleneck in the future. On the other hand, immediate action on a potential contingency task may incur a penalty in terms of wasted time if the contingency task did not actually impact the mission. When a contingency task is reported, the planner generates an updated plan that minimizes expected mission completion time by taking into account the probability of the contingency task impacting mission tasks, its effect on the mission, and its spatial location. We have characterized the performance of the algorithm through simulation experiments. We show that the proactive approach to contingency task management outperforms a conservative approach.