As a result of applying the previous steps, one obtains a fuzzy set
from the reasoning process that describes,
for each possible value , how reasonable it is to use this
particular value. In other words, for every possible value ,
one gets a grade of membership that describes to what extent this
value is reasonable to use. Using a fuzzy system as a
controller, one wants to transform this fuzzy information into a
single value
that will actually be applied. This
transformation from a fuzzy set to a crisp number is called a *defuzzification*. It is not a unique operation as different approaches are
possible. The most important ones for control are described in the
following.

- Centre of gravity method (COG)
- Centre of singleton method (COS)
- Maximum methods
- Margin properties of the centroid methods

Christian Schmid 2005-05-09