Anytime Planning for Optimal Tradeoff between Deliberative and Reactive Planning

Anytime algorithms are useful when the time available for computation is limited, that is, when there is a tradec~ between the time cost of further computation and the cost of using a solution that is only partially complete. Although machine planning presents this sort of problem, there has not yet been a treatment of anytime plAn-ing for the general case, that is, a treatment not tied to specific domains. In this paper, we present a model fur general-purpose anytime planning which allows the user to trade off the optimality of plans generated deliberatively with the speed of reactive plan generation. The anytime p|~n~er allows an interruption of hierarchical deliberative planning at the completion of any criticality level, and completes the plan st execution time using reactive planning. We illustrate the usefulness of this approach on a manufacturing domain.