Theory Of Fuzzy Logic

17 There are two ways to write the Fuzzy logic program in MATLAB commands window. One is using if-else function and second is using Fuzzy library function. Depends the convenient of a programmer, he or she can choose either method, but with Fuzzy library, the coding will become short and easy to understand.

2.2 Theory of Fuzzy Logic
Fuzzy logic was discovered and suggested by Lotfi Zadeh in 1965 [9]. At that time, the fuzzy was an extra theory of Boolean algebra. It was taught in many universities around the world under the subject of digital. Late in 1984, a fuzzy set was proposed by A.Smith in University of California [10]. Such fuzzy set is a set theory where currently many math students have study about it. In the set

Unlike in digital logic, only 0 or 1 two digits appear. Referring to Figure 2.4 to understand the Fuzzy logic, suppose that we have three different levels of speeds that are: slow, medium and fast. It is seen for every level of speed, there are intersection between the two. These intersections gives a point where the system might confused to determine whether it is slow or medium or fast. To overcome this problem, a programmer will set the level of membership in the program. For instance if speed is 50 and meet at the point of membership 0.5, then the programmer has to decide whether this 0.5 belongs to 1 or 0 or belong fast, medium or slow. Points of intersection between two variables are commonly happen in the Fuzzy set. The programmer usually avoid this by fixing one rule and determine which one has to follow. 22
2.3 Reviews the Applications of Fuzzy Logics
Fuzzy logic has many applications. The following shows the applications of fuzzy logics [14].

(a) Fuzzy rice cooker (b) Fuzzy washing

In the rice cooker, there is a heater that can generates heat to cook the rice. The amount of heats released are controlled by a controller build inside the rice cooker. The controller is loaded with fuzzy logic algorithm. A temperature is attached in the cooker. This temperature is used to detect the temperature of the heat and hence control the amount of current flows to the heat. The rice cooker with Fuzzy logic can cook the safely without over heat the rice. The Fuzzy logic also helps to turn OFF the rice cook when the rice is ready to