In: Proc. Advanced Summer Institute 95, Lisbon, Portugal, June 1995. 1995.
Abstract: A recently adopted view of complex industrial systems is the hybrid systems perspective. It consists of an attempt to model both plant and supervisory logic in the hope that unified treatment through suitable analytical or formal models can lead to better designs and performance analysis methodologies. We adopt the view that since hybrid systems are going to be based on one form of computer system or another, the specification of their requirements will consist of a mixture of control systems requirements and those of a software product. In this effort an important role will be played by formal modeling in supporting and assisting the building of an industrial (or enterprise, perhaps) control system in its widest possible interpretation. Thus, a mixture of control-related provisions and informatics-related prere-quisites lead to requirements that include: maintenance of stability of local loops, subprocesses, units, and of the whole plant at all times and under all conditions; the satisfaction of performance constraints; the ability to react to and handle unforeseen events; the support of distributed structures; the identification of a minimal adequate set of measurements whose processing can provide all necessary information regarding the operation and monitoring of the system; the satisfaction of synchronization requirements and timing constraints; efficient data handling; and of course high reliability and low costs.