The real-time supervisory control of an experimental manufacturing cell

Abstract

The manufacturing environment has changed dramatically. In the past, manufacturing systems were sufficiently simple, in most cases, to permit the use of intuitive and informal solutions in the development of supervisory control systems. The increasing level of automation, integration, and flexibility encountered in automated manufacturing systems renders formal approaches to the supervisory control system development a necessity, The controlled-automata based approach to supervisory control development considered in this work is one such approach. It offers important advantages over other approaches. It guarantees that: i) the resulting controlled behaviors do not contradict the behavioral specifications and are nonblocking and ii) the controlled behaviors are maximally permissive within the behavioral specifications. The work presented illustrates the applicability of the method to the supervisory control of industrial automated manufacturing systems. The paper provides an overview of the automated manufacturing field, and introduces supervisory-control-system development. The main concepts are illustrated through an example of a small manufacturing cell. The development of a supervisory control system for an experimental manufacturing cell is presented subsequently. Both centralized and modular supervision are considered. The automata models for the complete cell are provided together with the corresponding supervisors. The implementation of the resulting supervisory control system only required the use of "off-the-shelf" industrial control systems.