Distributed Rulebases For Real Time Process Control On The Shop Floor: The Metadatabase Approach

Abstract

Integrating real-time process control systems for material handling and other activities on the manufacturing shop floor is a key to highly automated factories. The iintegration must satisfy two basic requirements: adaptiveness and scalability. In particular, the real time systems need to have an architecture of integration that is responsive to changes and can be re-programmed on the fly. They also should be made compatible with enterprise-level databases. Theses requirements still present problems to the integration technology. A case in point is real time material handling in automated porcelain plate production. A solution to some of the problems is developed in this paper, using the Metadatabase Model (Hsu and Rattner, 1990; Hsu et. al., 1991; Hsu et. al., 1992). It entails (1) a(cluster of)central rulebase(s)structured as metadatabases for the integration environment; (2) a distributed rule-based shell sysem implementing the control knowledge contained in the rulebase(s)for individual real time processes; and (3) an execution model managing the the global knowledge and these shells. The original metadatabase model is extended to allow for both database integration and real time process integration. A particular software method, the real time rule-oriented programming environment (RT ROPE), is devised to provide a unifying core method to the whole enterprise, and thereby facilitate scalability and adaptiveness.