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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 !