REPRESENTATION OF PROCESS TRENDS .1. A FORMAL REPRESENTATION FRAMEWORK

A formal methodology capable of transforming time-records of process variables into meaningful and explicit descriptions of process trends in real-time is presented in this paper. The representation is based on the formal definition of "temporal episodes," which provide descriptions of trends by constructing "histories of episodes" making explicitly all the important "domain landmark values" specified by the user as well as the "geometric landmark values" generic to trends. Model inaccuracies are confined by establishing specific measures of information lost in the descriptions and keeping them below those of the process models. Despite the simplicity of the representation primitives, it is shown that the representation can provide complete, correct, robust and very compact models for process trend histories. In contrast to pure qualitative descriptions, the new representation contains sufficient quantitative information to allow for powerful inferences of the trends of the unmeasure variables. © 1990.