| One essential task of implementing flexible manufacturing systems (FMS) at the factory level is to achieve automatic control. This requires an appropriate control model that can be used not only as a tool for studying and analyzing control problems, but also as a platform for control software development. In this research, the Extended Moore Machine Network (EMMN) model is introduced using a distributed and bottom-up modeling approach. The basic concept of the EMMN scheme is to represent a complex system as a set of interconnected abstract machines. The global behaviors of an EMMN can be defined as a regular language which provides the basis for discrete event control. Using object-oriented methodology, the EMMN model is implemented as a formal framework for designing and specifying FMS control systems. An EMM is constructed as an object that possesses its own identity, states and interface functions. The communication within an EMMN is realized through message passing among the objects. A multi-level implementation scheme is proposed to facilitate a systematic transition of EMMN from design and specification to prototyping and verification at different system levels. The feasibility of the EMMN is demonstrated via modeling the FMS in the CIM laboratory at Penn State University. |
