fuzzylogic nav

8/6/2019 fuzzylogic naV

1/19

ADVANCED FUZZY CONTROL SYSTEMS

NAVEEN TAMANAM(EEE)

B.TECH


2/19

Overview of Fuzzy logicAdvanced control systems by fuzzyconclusion

2

Contents


3/19

3


4/19

I ntroduction to fuzzy

Fuzzy Logic - 1965 Lotfi Zadeh, Berkely

Definition : A form of knowledge representation suitable for notions that cannot be defined precisely, but which depend upon their contexts.

4

Fuzzy logic is a form of multi-valued logic derived from fuzzy set theory


5/19

5

According to Aristotles logical calculus

there are 2 truth valuesi.e true or false

Similarly boolean algebra have

i.e 1 or 0in modern systems there 3 values

* true , fault and unknown

but in fuzzy logic there are infinite truthvalues range form 0 to 1

n>2 in multi valued logic

where n=number of truth values


6/19

logic illustration

6

Take the glass of having water

From boolean logic we can representonly 2 states

Logic 1 Logic 0

fillempty

But in fuzzy logic we can representeach and every condition also

Logic 1 for fully fill

Logic 0 for empty

0.75


7/19

7

TRAD I TI ONAL REPRESENTAT I ON OFLOG I C

Slow Fast

Speed = 0 Speed = 1 bool speed;

get the speed

if ( speed == 0) {// speed is slow}else {// speed is fast}


8/19

8

FUZZY LOG I C REPRESENTAT I ON

For every problemmust represent in termsof fuzzy sets.

What are fuzzy sets?

Slowest

Fastest

Slow

Fast

[ 0.0 0.25]

[ 0.25 0.50 ]

[ 0.50 0.75 ]

[ 0.75 1.00 ]


9/19

9

FUZZY LOG I C REPRESENTAT I ON CONT.

Slowest Fastestfloat speed;get the speed if ((speed >= 0.0)&&(speed < 0.25)) {// speed is slowest}else if ((speed >= 0.25)&&(speed < 0.5)){

// speed is slow}else if ((speed >= 0.5)&&(speed < 0.75)){// speed is fast}else // speed >= 0.75 && speed < 1.0{

// speed is fastest}

Slow Fast


10/19

Fuzzy setFuzzy sets are sets whose elements havedegrees of membership

Definition

A fuzzy is a pair of (A ,m) where A is a set &m:A [0 ,1]

X is called not included in the set (A,m) if m(x)=0,x is fully included if m(x)=1

And x is a fuzzy number if 0


11/19

11

OR I GI NS OF FUZZY LOG I C

Traces back to Ancient Greece

Lotfi Asker Zadeh ( 1965 )

y First to publish ideas of fuzzy logic.

Professor Toshire Terano ( 1972 )

y Organized the world's first working group on fuzzy systems.

F.L. Smidth & Co. ( 19 8 0 )y First to market fuzzy expert systems.


12/19

12

Advanced control system by fuzzy logic

Fuzzy Logic provides a more efficient and resourceful

way to solve Control Systems.

Some Examplesy Temperature Controller

y Anti Lock Break System ( ABS )


13/19

13

Anti lock break systemThis system is work on the fuzzy logic

This is a simple control systemthe control is done by the fuzzy set

members

the system is controlled by speed andtemperature


14/19

14

The block diagram of fuzzy control


15/19

15


16/19

16


17/19

17

ANT I -LOCK BRAKES

Anti-Lock

Brake Module

Speed

Sensor

PressureValve Dump/VentValve

Master Cylinder Assembly

AntiLock

12V


18/19

18

CONCLUS I ON

Fuzzy logic provides an alternative way to represent

linguistic and subjective attributes of the real world in

computing.I t is able to be applied to control systems and other

applications in order to improve the efficiency and

simplicity of the design process.


19/19

19

fuzzylogic nav

Documents