Recovery scheduling for industrial processes using graph constraints

This paper considers a class of scheduling problems cast for processes that consist of several interconnected subprocesses. We model the temporal constraints (On-Off status) on each subprocess using labeled directed graphs to form the admissible set of schedules. Furthermore, we consider physical constraints inherent in the process. We approach to the scheduling problem as a safe steering problem with integer actions and utilize the reachability mappings for constraints. Consequently, we construct the safe recovery schedules that guarantee constraint satisfaction while steering the tank levels as desired. The proposed approach is illustrated in a simplified whey separation process case study.