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

CHAPTER FIVE 
5 CONCLUSIONS AND RECOMMENDATIONS 
5.1 Conclusion
In this thesis, temperature control of glass tempering resistance furnace is presented. Furnace 
is a nonlinear and time-varying complex system. After proper assumptions and approximations 
are made to linearize the mathematical equations describing the furnace, transfer function are 
obtained in frequency domain. The continuous time transfer function of the controlled plant 
and the PID controller is changed to its digital time equivalent. The sampling time is taken as 
0.1 second. The results of traditional PID temperature controller are not satisfactory to the 
higher degree of accuracy condition. Even it introduces steady state error to the system, fuzzy 
control not only has the prominent advantage in complex, time-varying and nonlinear system 
control but also don't need the mathematical model of controlled object. 
Fuzzy logic controller is proposed to tune the parameters of PID controller for temperature 
control of glass tempering resistance furnace, which has the advantages of PID control and 
fuzzy control. Both the transient and steady state performances of the controller are improved 
by increasing the number of membership functions 
A model that represents the glass tempering resistance furnace was developed. The 
performance of the proposed fuzzy PID and PID controller is tested through simulation studies 
using MATLAB/SIMULINK. It is observed from the simulation results that the average 
overshoot is 2.129%, rising time 45 seconds and the settling time is 180 seconds with the 
proposed fuzzy PID controller while overshoot is 16.13%, rising time is 44 seconds and settling 
time is 290 seconds with traditional PID controller. 
The proposed fuzzy PID controller is able to maintain the temperature of a glass tempering 
furnace within tolerable limits in spite of the parameter variation like delay time, time constant 
and DC gain. Furthermore, the capability of disturbance rejection is cheeked by giving step 
signal after settling time and it founded better than traditional PID. 

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Fuzzy PID Based Temperature Control of Electric Furnace for Glass Tempering Process
M.Sc. Thesis, Addis Ababa University, December 2016 
64 
The shape and distribution of the membership functions used in the design of fuzzy controller 
should be chosen with care to achieve system stability and robustness.