Design of Genetic Fuzzy Logic based Hybrid Temperature Controller and comparison with other Controllers Ashish Singh 1 , Dr. S. Chatterji 2 , Ritula Thakur 3 , 1. Lecturer, Department of Electronics Engineering, Board of Technical Education, Uttar Pradesh, Lucknow, Uttar Pradesh, India - 247776. 2. Professor and Head, Electrical Engineering Department, National Institute of Technical Teacher’s Training and Research, Chandigarh, India-160019. 3. Assistant Professor, Department of Electrical Engineering, National Institute of Technical Teachers Training & Research, Chandigarh, India -160019. Abstract - Water bath systems are nonlinear in behaviour thus conventional controllers like P, PI, PID are not so efficient. The Fuzzy Logic Controller has found better than PID in temperature control of water bath system in literature because the FLC processes user-defined rules governing the system, it can be modified easily to add, improve or alter system performance. This work presents Genetic Algorithm for the optimization of Fuzzy Logic Controller rule base for the temperature control of water bath system with goal of Zero response error. MATLAB is used for the simulation with Genetic Algorithm toolbox. Simulation results show that performance of Fuzzy Controller improves when optimized by Genetic Algorithm. A comparison has been made among controllers studied. Keywords: PID Controller, Fuzzy Logic Controller, Genetic Algorithm. 1. INTRODUCTION Temperature is the most important quantity which is measured and controlled in the industries and household appliances. Temperature controllers are needed in any situation requiring a given temperature be kept stable. Some of the biological processes, certain chemical reactions, and even electronic circuits perform best when they are carried out within limited temperature ranges. These processes, no matter it is a process of large industrial plants, or a process in home appliance, share several unfavorable features such as non-linearness, interference, dead time, and external disturbance, etc. Due to these internal and external disturbances operating temperature of the process varies continuously. In order to get the optimum result, the operating temperature of the process has to be controlled within specified limits. In order to optimize the process, a temperature controller is needed. The aim of this work is to control the temperature of the water bath at the desired set point and thereby optimize the process. This research work shows the design of temperature controller for water bath using PID, FLC and the optimization of FLC rule base using Genetic Algorithm. Then the comparison has been made and final conclusion has been drawn. 2. DEFINING PROBLEM Changes of temperature of a water bath is one of the industrial problems needed to be controlled. The continuous time temperature control system [1] is described as ( ) = ( ) + 0 − ( ) ……………….(1) where t denotes time, f(t) is heat flowing into the system, y(t) is output temperature in 0 C, Y 0 is the room temperature (assumed constant for simplicity), C denotes system thermal capacity and R is the thermal resistance between system border and surroundings. Assuming R and C constant, obtaining the pulse transfer function for (1) using step input, the result obtained is represented by equation (2). y(k+1)=a(Ts)y(k)+b(Ts)u(k) ……………….(2) where k is the discrete time index u(k) and y(k) represent the system input and output respectively and Ts is the sampling period. Denoting by and some constant values depending on R and C, so that parameters can be expressed by = − () and b(Ts) = (1 − − ) …..…………..(3) For simulation the parameters α=1.00151E-4 and β=8.67973E-3 and Y 0 =25 0 C, which are obtained from a real water bath plant. Now the simulated system is 477 Vol. 3 Issue 2, February - 2014 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 www.ijert.org IJERTV3IS20453 International Journal of Engineering Research & Technology (IJERT)