A real time expert system environment for process control

Abstract

Process control of complex systems is one of the most interesting frameworks to apply new developments of expert systems. Intelligent tasks working together with traditional control tasks under real time contraints will permit the perfect marriage of both fields. However most of the techniques needed for this purpose are not ready: parallel inference, fast and efficient temporal representation and reasoning, guaranteed response time in an inference process, etc. In this paper a real time expert system for process control, called RIGAS, is described. The system is based in a set of tasks, described in the QU1SAP language, a scheduler with intelligent policies, an agenda where instantaneous, delayed and periodic events are managed, and two sets of objects: application and control. Application objects are temporal objects mapping the real objects, while control objects are entities offering classical or rule-based regulators. A first prototype of the system written in Smalltalk as well as an application to the control of a cement kiln are detailed in the paper.