System approach to design generic software for real-time control of flexible manufacturing systems

Potentially, flexible manufacturing systems (FMSs) possess the ability to attain efficiency and versatility in small batches, variable mix production. However, the FMS potentiality is not yet fully used, because of the high cost of specific control software. Hence, a generic software, usable in an arbitrary FMS, producing an arbitrary part mix, appears as an important means to minimize programming and re-programming effort. In this context, modeling and control problem formalization emerge as a main issue. In this paper the authors refer to Zeigler's system-theoretic formalism for modeling the dynamics of a generic FMS at the job release and job how levels. The authors' discrete event dynamic system (DEDS) model establishes an abstract comprehensive framework for developing a generic control software at such levels. The model is able to represent both hardware/software components of the FMS and processing activity plans with a common "language". A modular structure underlies the description of both the shop-floor dynamics and control rules. So, the software architecture emerges as a direct consequence of the proposed approach and consists of three main parts: the system state knowledge base, the job release manager and the job flow manager.