Utility-based plan insertion for continuous resources

In this paper, we consider the problem of evaluating plan fragments for insertion into an existing plan. Preparing a plan that is robust to variations in continuous resources requires considering the uncertainty over these resources. For some situations, it is impractical to add branches to the plan a priori, because such situations may arise at any of a large number of points in execution. Adding all these potential branches to an existing plan would require an immense computational effort and result in a huge plan. In such a case, it makes more sense to precompute a plan fragment to react to such a situation and allow the execution system to insert the plan fragment into its current plan when appropriate. The problem can thus be seen as a restricted form of plan merging, but with the addition of uncertainty and continuous resources, and the criterion of maximizing utility rather than absolute goal achievement. We formalize the problem and introduce an efficient solution method, incremental bounds refinement, that iteratively narrows bounds on the expected value of adding a branch until it can be discriminated from the original plan.