Cl. Chen et al., Theoretical analysis of a fuzzy-logic controller with unequally spaced triangular membership functions, FUZ SET SYS, 101(1), 1999, pp. 87-108
The mathematical analysis concerning the explicit input/output relation of
the fuzzy logic controller (FLC) is addressed in this article. Under the as
sumption of simple rule mapping and the use of arbitrarily located triangul
ar fuzzy partitions as the membership functions, the inferred output of the
FLC can be decomposed into two terms: the global multilevel relay and the
local nonlinear compensator. The ultimate control behavior of this FLC and
the equivalence to nonlinear proportional-integral (PI) controller, as the
number of linguistic terms are approaching to infinity, are also investigat
ed. The local stability criteria for PI-type FLCs are derived and the globa
l stability properties for PD-type FLCs are established. This analysis is a
generalization to previous related research works where the FLC is charact
erized by equally spaced triangular fuzzy partitions on the universal sets.
(C) 1999 Elsevier Science B.V. All rights reserved.