Opportunistic planning for increased plan utility

This paper explores the execution of planned missions in situations in which opportunities to achieve additional utility can arise during execution. The missions are represented as temporal planning problems, with hard goals and time constraints. Opportunities are soft goals with high utility. The probability distributions for the occurrences of these opportunities are not known, but it is known that they are unlikely so it is not worth trying to anticipate their occurrence prior to plan execution. However, as they are high utility, it is worth trying to address them dynamically when they are encountered, as long as this can be done without sacrificing the achievement of the hard goals of the problem. We formally characterise the opportunistic planning problem, introduce a novel approach to opportunistic planning and compare it to an on-board replanning approach in an example domain involving autonomous underwater vehicles.