Quality Metrics to Evaluate Flexible Timeline-Based Plans

Timeline-based Planning has been successfully applied in several contexts to solve Planning and Scheduling (P&S) problems. A key enabling feature of the timeline-based approach to planning is its capability of dealing with temporal flexibility. Temporal flexibility is an important feature in real world scenarios. Indeed, it can be exploited by an executive system for robust on-line execution of flexible plans in order to absorb possible delays during the execution. In this regard, it is useful to define quality metrics to evaluate the robustness of flexible timeline-based plans. In this paper, a set of quality metrics for flexible timelinebased plans are defined and discussed when applied to a specific timeline-based framework. In fact, we consider the framework EPSL, developed to support the design of P&S applications, that allows the definition of different planners endowed with specific heuristics. Then, an experimental analysis is presented exploiting the planners to solve planning problem instances related to a real-world manufacturing case study. And, finally, an evaluation of planners performance is presented and discussed comparing results also considering robustness of generated plans.