Fuzzy logic

Fuzzy logic is an attempt to get the easy design of logic controllers and yet control
continuously-varying systems. Basically, a measurement in a fuzzy logic system can be
partly true, that is if yes is 1 and no is 0, a fuzzy measurement can be between 0 and 1.
The rules of the system are written in natural language and translated into fuzzy logic.
For example, the design for a furnace would start with: “If the temperature is too high,
reduce the fuel to the furnace. If the temperature is too low, increase the fuel to the
furnace.”


Measurements from the real world (such as the temperature of a furnace) are converted to
values between 0 and 1 by seeing where they fall on a triangle. Usually the tip of the
triangle is the maximum possible value which translates to “1.”
Fuzzy logic then modifies Boolean logic to be arithmetical. Usually the “not” operation is
“output = 1 - input,” the “and” operation is “output = input.1 multiplied by input.2,” and
“or” is “output = 1 - ((1 - input.1) multiplied by (1 - input.2)).”


The last step is to “defuzzify” an output. Basically, the fuzzy calculations make a value
between zero and one. That number is used to select a value on a line whose slope and
height converts the fuzzy value to a real-world output number. The number then controls
real machinery. If the triangles are defined correctly and rules are right the result can be a good control system. Fuzzy electronics is an electronic technology that uses fuzzy logic instead of the twovalue logic more commonly used in digital electronics.

When a robust fuzzy design is reduced into a single, quick calculation, it begins to
resemble a conventional feedback loop solution. For this reason, many control engineers
think one should not bother with it. However, the fuzzy logic paradigm may provide
scalability for large control systems where conventional methods become unwieldy or
costly to derive.