Supervisory Control of Discrete Event Systems in Manufacturing Industry

Abstract

Nowadays, Supervisory Control Theory (SCT) is a very used technique dedicated to produce a controller for Discrete Event Systems (DES), like intelligent manufacturing systems, robot systems, transport systems, IT& C etc. The resulted DES controller is also considered as supervisor. Generally, SCT involves formal languages and control concepts for performing supervisor activities. When involving SCT elements, a plant can be modeled by using control structures. This command structure is an event sequence generator. Any uncontrolled behavior of that plant is defined by these generated sequences. The desired controlled behavior of that system is defined by specifications. When applying SCT, a supervisor can easily be synthesized for avoiding plant entering on undesired states. After the synthesizing process, the computed supervisor can be implemented in order to perform all control tasks. The Programmable Logic Controllers (PLC) are, today, mostly used to realize control tasks in contemporary industry due to some clear assets. It is also obvious that, the supervisor is commonly implemented not only by means of PLCs or dedicated industrial embedded systems. The most popular computing language for programming PLCs is Ladder Logic Diagrams (LLD). The supervisors in automatic form can be easily compiled to an LLD compliant code. In this, report fundamental information about SCT is presented. A small manufacturing system consisting of two machines and a buffer is described as an example. All integration procedures applied for supervisor techniques are also provided.