Transcript Chap 1. Introduction

Chap 1. Introduction
Outline
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1.1 What is Fuzzy Logic?
1.2 The History of Fuzzy Logic
1.3 Motivations
1.4 Why use fuzzy logic to control?
1.1 What is Fuzzy Logic?
• Two different senses:
– Narrow sense(狹義): fuzzy logic refers to a logical
system.
– Broad sense(廣義): fuzzy logic refers to all of the
theories and technologies.
• An Example : “warm room temperature”
– Classical set theory: An interval (e.g. [70°F ~ 78°F]).
– Human interpretation : a gradual transition from
“not warm” to “warm.” In order to achieve this,
 Fuzzy sets.
1.1 What is Fuzzy Logic? (cont’)
• Classical set vs. Fuzzy set
1.2 The History of Fuzzy Logic
• 1964 :
– The birth of fuzzy set theory in 1964 by
Zadeh.
• 1965-1975:
– A decade of theory development
• 1976-1987:
– Pioneers of industrial Applications
• 1987-present:
– The fuzzy boom
1.3 Motivations
• Two objectives:
– Developing and analyzing complex systems are
difficulties.  cost-effective.
– Human reasoning can utilize concepts and
knowledge.  artificial intelligence (AI).
• This characteristic of fuzzy logic
– It not only provides a cost-effective way to model
complex systems involving numeric variables but
also offers a qualitative(定性的)description of the
system that is easy to comprehend(包括).
1.3 Motivations (cont’)
1.4 Why use fuzzy logic to control?
• Answers:
– 1). Fuzzy logic can be used for controlling a process
that is too nonlinear or too ill-understood.
 To deal with complex systems.
– 2). Fuzzy logic enables control engineers to easily
implement control strategies used by human
operators.
 The ease of describing human knowledge.
1.4 Why use fuzzy logic to control? (cont’)
• 1.4.1 Modus operandi(工作方法)
– Fuzzy logic is a rule-based systems.
– Image Stabilization
• There are no known algorithms. For this reason, one
would rely on rules or heuristics as the basis for
implementation of a control strategy.
• An heuristic rules is given：
IF all motion vectors are almost parallel and their time differential is
small, THEN the hand jittering is detected and the direction of the hand
movement is the direction of the moving vectors.
1.4 Why use fuzzy logic to control? (cont’)
1.4 Why use fuzzy logic to control? (cont’)
1.4 Why use fuzzy logic to control? (cont’)
• To summarize:
– Absence of a readily available algorithm for
control leads to the use of rules as the basis for
implementation of control strategy.
– Fuzzy logic deals with uncertainty(不確定)
regarding the applicability(適用性) of heuristic
rules and accounts for imprecision in
measurements.
1.4 Why use fuzzy logic to control? (cont’)