A design methodology of constraint-based fuzzy logic controller

Abstract

Constraint-based fuzzy logic controllers (CFLCs) have been recognized as a unified framework of control system design. Arbitrary types of constraints are allowed in a CFLC to specify the desired states of a plant. The purpose of this paper is to present a design methodology of CFLCs, transforming the intention of a control system into a network of fuzzy constraints. The task of designing a CFLC could be viewed as a process of incremental constraint-based problem-solving, namely a fuzzy constraint refinement problem. Specifically, a schema could be derived for the configuration of a CFLC; after that, constraints can be gradually added (or removed) into the schema until the performance requirements are met. Based on this framework, we have successfully designed a CFLC for modeling a simplified rotary cement kiln that has both nonlinear and time varying characteristics of a plant.