Fuzzy optimal control of structures

Fuzzy numbers can be used to model structural uncertainties. In addition, structures can be modeled using the fuzzy finite element method. In order to design an optimal controller for the fuzzy modeled structures, fuzzy optimal controller design should be explored. During the past few years, some researches have been trying to design fuzzy optimal controllers based on the Takagi and Sugeno model. In this paper, a different structural model based on fuzzy finite element analysis is presented. The corresponding fuzzy optimal control theory is also explored. In most practical applications the structural and material parameters vary considerably and are subject to uncertainties, mainly due to the uncontrollable aspects associated with the manufacturing and assembly processes associated with materials (especially composite materials). The probabilistic methods cannot be applied since the probability distributions of the uncertain parameters are not usually known. Also, in some situations, the parameters are known only in linguistic form. A fuzzy finite element approach has been developed for the analysis of structures with fuzzy parameters. Based on the deterministic optimal control theory, a fuzzy optimal control theory is developed to act as a regulator or a tracking system. A 2-dimensional truss and a 3-dimensional composite box beam are presented to demonstrate the feasibility and applicability of the methodology presented.