Although the fuzzy logic controller has been adopted in many engineeri
ng applications, its performance is not guaranteed since there is no d
efinite stability analysis. It may be the main factor that we hesitate
to adopt the FLC in critical applications. In this paper, a guideline
of systematic analysis and design of an FLC is presented for guarante
eing the stability and/or the performance. Based on the well-developed
variable structure system theory, we account for the relationship bet
ween the tracking accuracy of a control system and the I/O fuzzy set m
embership shapes of the FLC. It is also possible to explain the perfor
mance or the stability of commonly used FLCs through the proposed guid
eline for the design and analysis.