Composite schedules of manufacturing cells and their timed Petri net models

In composite schedules, several (identical or different) parts enter and leave a manufacturing cell in each cycle. A systematic method of generating all composite schedules is proposed, and it is shown that the generated schedules can easily be transformed into timed Petri net models. Invariant analysis of these timed net models provides performance characteristics of the cell. The characteristics are obtained in analytical (or symbolic) form, so they are applicable to a wide spectrum of specific cases. Simple examples illustrate an application of the proposed approach to a robotic cell with three machines.