Practical design of nonlinear fuzzy controllers with stability analysis for regulating processes with unknown mathematical models - Comment

It is shown in this note that the fuzzy controller with (locally) linear control rules used in Ying (1994) cannot be linearized around the origin, and therefore local stability of closed-loop systems including this type of fuzzy controller cannot be analyzed by means of the Lyapunov's first method. Besides, it is proved that, with another choice of inference law, the fuzzy controller with (locally) linear control rules can be linearized in a neighbourhood of the origin. Copyright (C) 1996 Elsevier Science Ltd.