Sequential modelling of the planning and scheduling problems of flexible manufacturing systems

Research on the planning and scheduling issues of flexible manufacturing systems (FMS) has not been sparse. Most, if not all, studies, however, have focused on either developing the planning model or examining the performance of different scheduling rules. To date, the FMS planning and scheduling problems have not been studied together, though they are highly interrelated. This paper takes a first step to simultaneously address the planning and scheduling problems of flexible manufacturing systems. The problems are solved as a hierarchical process. The authors first integrate and formulate batching, loading, and routeing, three of the most important FMS planning problems, as a 0-1 mixed integer program. According to the optimal decisions provided by the integrated planning model, they then develop an off-line scheduling scheme that is capable of generating detail parts sequencing in the sequence independent environment (i.e. the operations are not constrained by a process sequence). Finally, they suggest several extensions and future research directions.