The document provides an introduction to fuzzy controllers, including common methods used in fuzzy logic systems. It discusses max-min inference and centroid defuzzification, and explains that fuzzy control system design uses empirical trial and error methods. As an example, it describes a fuzzy controller for a steam turbine, defining its input and output fuzzy sets and sample rules. It then outlines four common methods for defuzzifying fuzzy output functions: max membership, centroid, weighted average, and mean max membership.