Fuzzy Logic

ByAstha Dangwal

Roll no.- 17

INTRODUCTION

What Is Fuzzy Logic????

¤ A multivalued Logic !

¤ Fuzzy logic deals with intermediate values between 0 and 1.

¤ It gives us the degree of ‘truthfulness’

¤ A way to make use of natural language in logic

¤ A linguistic variable such as temperature may have a value such as hot or its antonym cold

HISTORY OF FUZZY LOGIC!¤ During ancient times it was

thought that either a preposition is entirely true or entirely false.

¤World is full of contradiction and there is a degree of truth and a degree false at the same time.

¤ Founder of Fuzzy Logic:

Dr. Lotfi A Zadeh

Fuzz

y’s

Past

!

FUZZY OPERATORSRules are usually expressed in the form:

IF variable IS property THEN action

For example, a simple temperature regulator that uses a fan might look like this:

웃 IF temperature IS very cold THEN stop fan 웃 IF temperature IS cold THEN turn down fan

웃 IF temperature IS normal THEN maintain level

웃 IF temperature IS hot THEN speed up fan

FUZZY LOGIC OPERATIONS

NEGATION

AND (Intersection)

OR (Union)

FUZZY DEVELOPMENT TOOLS

SOFTWARE

Software Development toolsA programming language to code the entire

fuzzy sytem manually.

A fuzzy pre-compiler.

Use of Visual Design Interface.

FUZZY DEVELOPMENT TOOLSHARDWARE

Hardware Development ToolsFirst Generation Fuzzy Logic Processors

-used fuzzy logic gates.-not popular

Second Generation Fuzzy Logic Processors-Could connect to the host micro-controller unit-Expensive

Third Generation Fuzzy Logic Processors-Integrate fuzzy logic operators within microcontrollers-Speedy-Compact codes

HOW IS FUZZY LOGIC USED?웃 Define the control objectives and criteria

웃 Determine the input and output relationships

웃 Break the control problem down into a series of IF X IS Y THEN Z

웃 Create FL membership functions that define the meaning (values) of Input/Output terms used in the rules.

FUZZY CONTROLLERS 웃 Fuzzy controllers are able to control problems for which

construction of accurate mathematical models are difficult and expensive.

eg. IF temperature IS hot THEN fan speed is high

웃 Fuzzy Controllers are robust.

웃 New sensors can be easily incorporated.

웃 Any reasonable number of inputs can be processed (1-8 or more) and numerous outputs (1-4 or more) generated.

웃 Fuzzy Logic can control nonlinear systems

BLOCK DIAGRAM OF FUZZY CONTROLLER

APPLICATIONS OF FUZZY LOGICTemperature Control (heating/cooling)

Ever wondered how the AC works?Auto Focus on the Camera

how does the camera knows what to focus on?Elevators

Fuzzy logic helps to reduce waiting time.Subways

Fuzzy-logic controllers make subway journeys more comfortable with smooth braking and acceleration.

Washing Machines

CASE STUDY– FUZZY TRAFFIC CONTROL

The Fuzzy controller is supposed to change the cycle time depending upon the densities of cars behind green and red lights and the current cycle time.

BACKGROUND웃 In a conventional traffic light controller,

the lights change at constant cycle time.웃 It would be more feasible to pass more

cars at the green interval, if there are fewer cars waiting behind the red lights.

웃 Obviously, a mathematical model for this decision is enormously difficult to find.

웃 However, with fuzzy logic, it is relatively much easier

FUZZY DESIGNThe first sensor behind each

traffic light counts the number cars coming to the intersection.

The second counts the cars passing the traffic lights.

The distance D, chosen to be 200ft., is used to determine the maximum density of cars allowed to wait in a very crowded situation

Density between E-W:(s1-s2)+(s5-s6)/400.

EVALUATION OF FUZZY TRAFFIC CONTROLLER

P.S : Machine BeatsMan!

ADVANTAGES & DISADVANTAGES OF

FUZZY LOGICAdvantages of fuzzy logic

- Allows the use of vague linguistic terms in the rules.-Can accept multiple inputs and generate multiple results.-No complex mathematical model is required.

Disadvantages of fuzzy logic– Difficult to estimate membership function– There are many ways of interpreting fuzzy rules,combining the outputs of several fuzzy rules and

defuzzifying the output.

FUTURE SCOPE

The future is bright, the future is fuzzy!

¤ Robots with a humanlike repertoire of behaviour.

¤ Computers that understand and respond to normal human language.

¤ Machines that write interesting novels and screenplays in a selected style.

¤ Molecule-sized soldiers of health that will roam the blood-stream, killing cancer cells and slowing the aging process.

Thankyou !