Specification of a Flexible Manufacturing System Using Concurrent Programming

Because of the growing complexity, the design of and reasoning about modern industrial systems becomes increasingly difficulty. In order to understand and estimate the dynamic system behaviour, appropriate models have to be used. In many cases, existing mathematical models like queuing networks, Markov chain models, or perturbation analysis cannot be applied. In such cases, usually a model is constructed that can be validated by means of computer simulation. Since industrial systems exhibit concurrency, formalisms developed to reason about con current systems are also well suited for developing models in this specific application area. Models of systems can be expressed, for instance, in terms of Petri nets or in terms of programs written in a concurrent programming language, like Timed CSP. Both approaches, originating from computer science, are increasingly often applied in modelling of manufacturing systems. In this paper, we present a simple modular approach to the specification of (discrete) industrial systems that is based on concurrent programming. As an illustration, we present a model of a flexible manufacturing cell. The specification language used is modular and, therefore, allows for hierarchical modelling. To specify the information and control flows, a VDM-like notation is used.