Satisfying Resource Constraints in Space Missions by On-line Task Reconfiguration

This paper addresses the problem of robust plan execution in the context of exploration mission plans carried on by planetary rovers. In order to deal with limited computational resources, and with limited rover’s autonomy (the rover is not allowed to change its plan), the paper proposes a novelmethodology to cope with contingencies rising at execution time. The approach aims at reconfiguring on the fly the plan by changing the parameter configuration of the actions still to be executed. By exploiting an enriched action representation based on the notion of execution modalities, the ReCon system is able to (i) early detect the violation of mission resource constraints, (ii) find (if any) a new assignment of modalities to preserve the mission plan constraints. ReCon uses constraint satisfaction techniques both for plan consistency and plan reconfiguration. Finally, the paper reports a preliminary set of experimental results which in practice confirms the feasibility and the advantages of the approach.