Fuzzy Logic

Definition

Fuzzy logic is an approach to computing based on "degrees of truth" rather than the usual "true or false" (0 or 1) Boolean logic on which the modern computer is based.

Application Area

Aerospace

Altitude control spacecraft

Satellite altitude control

Flow and mixture regulation in aircraft deicing vehicles

Automotive

Trainable fuzzy systems for idle speed control

Improving efficiency of automatic transmissions

Electronics

Air conditioning systems

Washing machine timing

Vacuum cleaners

Finance

Banknote transfer control

Fund management

Stock market predictions

Securities

Decision systems for securities trading

Various security appliances

Architecture

Fuzzification Module

It transforms the system inputs, which are crisp numbers, into fuzzy sets.

Knowledge Base

It stores IF-THEN rules provided by experts.

Inference Engine

It simulates the human reasoning process by making fuzzy inference on the inputs and IF-THEN rules.

It simulates the human reasoning process by making fuzzy inference on the inputs and IF-THEN rules.

Algorithms

Define linguistic variables and terms.

Construct membership functions for them.

Construct knowledge base of rules.

Evaluate rules in the rule base. (Inference Engine)

Combine results from each rule. (Inference Engine)

Advantages

Mathematical concepts within fuzzy reasoning are very simple.

You can modify a FLS by just adding or deleting rules because of its flexibility

Fuzzy logic Systems can take imprecise, distorted, noisy input information.

FLSs are easy to construct and understand.

Fuzzy logic is a solution to complex problems in all fields

Disadvantages

no systematic approach to fuzzy system designing.

understandable only when simple.

only suitable for the problems which do not need high accuracy.

History

Study began since 1920s as infinite valued logic

Fuzzy logic was introduced by Lotfi Zadeh in 1965

A sub way system was built using fuzzy logic in Japan in 1987