Application of the mark flow graph to represent discrete event production systems and system control

condition systems, and several works2)•`4) have confirmed the wide modeling power of this tool. However, to model a specific system, we need to provide an interpretation, both for the MFG structural elements and the structure composed by these elements, up to an appropriate level to clearly model the features of the system. From this viewpoint, a hierarchical approach is adopted in which the system model at macro level is broken-down to a detailed level. This approach provides a systematic design procedure in which an interpreted MFG model is synthesized. With the resultant model the structural information of the whole system and the detail of each component are explicitly described. Therefore this concept is effective for representing discrete event production systems and system control. Firstly, we consider that discrete event production systems are represented by activity elements, distributing elements and the connections between these elements. After discussing the hierarchical structure of the activity elements, the production flow schema and an interpreted form of MFG are introduced as regulation and representation tools. Thereafter, several control rules are derived based on the MFG modeling method and its properties, in which problems such as resource allocation and conflict arbitration are discussed.