ABSTRACT
This chapter addresses various considerations of knowledge-based hierarchical control with direct reference to an industrial application. It explores a hierarchical model for knowledge-based control of a process plant. The degree of fuzziness is viewed as a means of classifying information and knowledge for various levels in the hierarchy. The degree of fuzziness of a fuzzy set is a measure of the difficulty of ascertaining the membership in the fuzzy set of the elements of the support set. Specifically, the system may be arranged into a functional hierarchy, with modules of similar functionality occupying a single layer. Each module will possess a fixed input-output structure, and will represent an object in an object-oriented paradigm. The total number of possible fuzzy states of a variable within a given knowledge base represents the fuzzy resolution of that variable. In particular, when the level is high and the level differential is high, then high-level information processing will be involved in general.
