Timed-MPSG: A Formal Model for Real-Time Shop Floor Controller

Abstract

The MPSG (message-based part state graph) model has been developed for the execution portion of shop-floor controllers that operate in a distributed and hierarchical control environment. It describes the behavior of a controller from the parts' point of view, and each part within the domain of the controller is in a particular 'state' as described by the MPSG for that controller. It is based on deterministic finite state automata and represents the execution module of shop- floor controller as a communicating finite state machine. However, there is still no consideration for handling the time in this framework. We propose an extension of temporal properties in MPSG to model the real-time shop floor controller. It has been christened as a Timed-MPSG. It is a novel approach to deal with the auto generation of real time based controller logic for hierarchical and distributed shop floor system. In this paper we have described the conceptual idea and formal model of Timed-MPSG with suitable examples.