Fuzzy pid based Temperature Control of Electric Furnace for Glass Tempering Process

2.3.2.3 FUZZY LOGIC CONTROL COMPONENTS 
The three main actions performed by a fuzzy logic controller are: 

Fuzzification 

Fuzzy processing 

Defuzzification 
As shown in Figure 2.5, when the fuzzy controller receives the input data, it translates it into a 
fuzzy form. This process is called fuzzification [17-19]. The controller then performs fuzzy 
processing, which involves the evaluation of the input information according to IF…THEN rules 
created by the user during the fuzzy control system’s programming and design stages. Once the 
fuzzy controller finishes the rule-processing stage and arrives at an outcome conclusion, it 
begins the defuzzification process. In this final step, the fuzzy controller converts the output 
conclusions into “real” output data and sends this data to the process via an output module 
interface. If the fuzzy logic controller is located in the PLC rack and does not have a direct or 
built-in I/O interface with the process, then it will send the defuzzification output to the PLC 
memory location that maps the process’s output interface module
. 
Figure 2. 5 Fuzzy logic controller operations 
FUZZIFICATION 

Fuzzification is the process of making a crisp quantity fuzzy[17][18]. It transforms the physical 

values of the error signal, rate of change of error which is input to the fuzzy logic controller, 
into a fuzzy set consisting of an interval for the range of the input values and an associate 
membership function describing the degrees of the confidence of the input belonging to this 
range. The conversion process is performed by a membership function. The purpose of this 
fuzzification step is to make the input physical signal compatible with the fuzzy control rule 
base in the core of the controller. Fuzzification consists of two main components: 

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Fuzzy PID Based Temperature Control of Electric Furnace for Glass Tempering Process
M.Sc. Thesis, Addis Ababa University, December 2016 
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