TEMPORAL MANAGEMENT USING RELATIVE-TIME IN KNOWLEDGE-BASED PROCESS-CONTROL

In this paper, a knowledge-based approach is proposed for the manageme nt of temporal information in process control. A common-sense theory o f temporal constraints over processes/events, allowing relative tempor al knowledge, is employed here as the temporal basis for the system. T his theory supports duration reasoning and consistency checking, and a ccepts relative temporal knowledge which is in a form normally used by human operators. An architecture for process control is proposed whic h centres on an historical database consisting of events and processes , together with the qualitative temporal relationships between their o ccurrences. The dynamics of the system is expressed by means of three types of rule: database updating rules, process control rules, and dat a deletion rules. An example is provided in the form of a life schedul er, to illustrate the database and the rule sets. The example demonstr ates the transitions of the database over time, and identifies the pro cedure in terms of a state transition model for the application. The d ividing instant problem for logical inference is discussed with refere nce to this process control example, and it is shown how the temporal theory employed can be used to deal with the problem. (C) 1997 Elsevie r Science Ltd. All rights reserved.