Message-based Part State Graphs: A formal model for shop-floor control implementation

This paper presents a formal model of the execution portion of shop-floor controllers that operate in a distributed control environment. This model, called a message-based part state graph (MPSG), represents the execution module of shop-floor controller as a communicating finite state machine. Individual controllers in a distributed environment communicate using the defined protocol to oversee floor operations. The aim has been to use this formal model as a basis for developing the control software. Known methods for generating lexical analysers based on the underlying deterministic finite automation model are used to generate the execution portion of shop-floor controllers. The implementation of the MPSG model in a hierarchical shop-floor control system is described.