Fuzzy controllers belong to the class of knowledge based sys- tems.
Fuzzy logic provides a mathematical formalism for this goal. An original method for the design and analysis of a fuzzy controller is pro- posed. The main idea is to apply an on-line adaptive algorithm to automatically adjust the parameters of the fuzzy controller, depending on its inputs and desired outputs. It is shown that a fuzzy controller can learn to approximate non-linear functions arbitrarily well. A new method for the extraction of linguistic rules from the adapted parameters is introduced.