Contraction of Fuzzy Control Rules, and its Application to Tobacco Dryer

Abstract

Recent studies on an improvement of fuzzy controls have shown that fuzzy variables in the antecedent had better exist successively. Then, fuzzy control rules will act mutually and continuously according to the change of the input data. Therefore, the rules had better not leave a blank to all combination of the fuzzy variables. In order to cope with increasing the number of rules, it becomes necessary to contract fuzzy control rules without changing the original control.
The present method defines the “and” conjunction of the antecedent not with the minimum operation but with the product of the grades of the input data. As the result, fuzzy control rules will cover a wider area respectively.
We apply this technique to the control of a tobacco dryer. The fuzzy PD controller in feedback control is represented by a single plane with 4 rules. In contracting the on-off control rules, we propose a coordinate transformation method of the input variables in order to reduce the number of rules without transforming the shape of the control surface.