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.

The authors propose an approach to workcell supervisory control strategy design based on the control theory for discrete event systems (DES). A framework for the modeling and supervisory control of timed DES is presented, in which the concept of forcing as a means of control is introduced, and where hard temporal behavior specifications may be treated. Within this framework, supervisory control strategies are designed according to production specifications and subject to control enforcement constraints.>

A novel approach to the control and supervision problem for groups of elevators has been successfully developed and tested by simulation. The control and supervisory tasks have been implemented using the blackboard approach to problem solving in which several knowledge sources cooperate, providing a very flexible problem solving framework. The blackboard shell control unit developed in this study uses a dual-level control structure and a comprehensive data structure for the knowledge source descriptors. The modularity of the control and supervisory system allows the control and supervisory strategies to be modified or extended simply by adjoining additional knowledge sources to the existing ones and tuning different knowledge source descriptors.>