Fuzzy logic is a form of logic that can handle more than two logic states. In conventional binary logic, there are only two logic states: 1 (True) and 0 (False).  In contrast, fuzzy logic can have a logic state that is in between being completely true and completely false.  In fact, the degree of truth can be quantified using fuzzy logic, by assigning a number between 0 and 1 to denote it.  Thus, the closer the fuzzy logic state value is to '1', the closer it is to being completely true.

Fuzzy logic was derived from 'Fuzzy Set Theory', a set theory wherein the membership of an element in a set (referred to as a 'fuzzy set') is expressed as a possibility rather than as a hard fact.  This is in contrast with the classical set theory, wherein an element can only be either a member of a set or not.

The mathematics of fuzzy logic has found its way into electronics technology, primarily because many real-world signals used in electronic control are continuous (analog and not digital) in nature.  Thus, the various real-world inputs to a typical electronic control system can not be represented merely as either a hard 'true' or a hard 'false'.  Fuzzy logic allows the the states of these inputs to assume values between 'true' and 'false', and facilitates the processing of these 'in-between' input levels so that the electronic system can come up with a more adequate output response.

For instance, an electronic control system that responds to the weight of a varying mechanical load can not simply categorize the continuously changing load as either 'heavy' and 'light'.  It is better off using fuzzy logic to process information using varying load values between 'heavy' and 'light'.  Another example is a control system that reacts to the heat emitted by its different components.  Instead of simply identifying a component as either 'hot' or 'cold', fuzzy logic can help in coming up with a more effective output response by using fuzzy logic values to represent the degree of heat emitted by each component. 

    

Figure 1.  Two appliances using Fuzzy Logic - a rice cooker (left) and a washing machine (right)

            

Fuzzy logic has been applied to a multitude of electronically controlled equipment and systems which include the following: air conditioners, automobile subsystems (ABS, cruise control, automatic transmissions), cameras, dishwashers, washing machines, elevators, rice cookers, and many more.  It has also been employed in many scientific and computer applications such as meteorology, pattern recognition, digital image processing, and video game artificial intelligence.

 

    

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