Supervisory control of flexible-manufacturing workcells that allow the production of a priori unplanned part types

Traditionally, the function of a workcell supervisor has been to coordinate the various elements comprising the workcell for the production of a specific a-priori set of parts using a predetermined set of machines. Correspondingly, current workcell supervisor synthesis methodologies assume that the part production mix remains constant. In practice, however, the product mix may change over time. New part types are required to be processed, while other (nominal) part types may be temporarily discontinued. The workcell supervisory control approach proposed in this paper is that of utilizing a pair of non-communicating independent supervisors, working in concert to achieve the production of nominal and a-priori unplanned-for new part types: nominal and complementary supervisors. The nominal supervisor is responsible for controlling the behavior of the nominal workcell, producing the set of a-priori planned part types, while the complementary supervisor controls the flow of the unplanned-for new part types, where each supervisor is synthesized individually