Abstract
In this paper, time-domain stability analyses on nonlinear control systems with various types of fuzzy controllers are discussed, in which a BIBO stability criterion and a global asymptotic stability criterion are given based on both boundedness and asymptoticity for solutions of the set of nonlinear inequalities with respect to characteristic quantities such as the quadrant components of three-dimensional input-output space of a fuzzy controller, positive or negative areas of an impulse response of a linear control object, and ultimate positive or negative bounds for input signals.Stability analyses for nonlinear control systems with a two-input or three-input and one-output fuzzy controller through four typical reasoning methods, i.e., the min-max-center of gravity method, the product-sum-center of gravity method, the functional reasoning method, and the Tsukamoto's method, are shown comparing the results due to the proposed method with those owing to other known stability criteria.As a result of the above, it is assured that the proposed method is systematically applied to every type of controllers with various reasoning methods and is also superior in stability ranges owing to the essential property of this proposed method.
