A simulation based optimization approach to real-time control and scheduling of flexible manufacturing systems

This paper proposes a unique framework for real-time control and scheduling of flexible manufacturing systems (FMS). This framework allows changes in the scheduling policy for short-term intervals in response to the dynamic status of operating FMS. Each time when rescheduling is needed, the Standard Clock (SC) simulation is first employed to evaluate the performance of a set of scheduling policies for a short planning horizon. Ordinal Optimization concept is then used to select a scheduling policy. Due to the use of Standard Clock technique and Ordinal Optimization concept, the advantages of this framework include: (1) a drastic reduction of the time needed for decision making; and (2) as the problem scale increases, the decision making time increases linearly rather than exponentially. These two features indicate that this framework has a potential to be implemented in real FMS settings.