Design and Development of an Auto-Tuning Proportional-Integral-Derivative Controller using Genetic Algorithm

The polymerization of resin adhesives, which is highly nonlinear, is chosen as a process control system. When phenol and formaldehyde are mixed, a sudden and unpredictable heat is produced due to an exothermic reaction, which could cause the deviation of process temperature and hence diminish the product quality. Hence, temperature control is necessary for exothermic batch reactor. The most common approach used in industries is the proportionalintegral-derivative (PID) controller, which is tuned by the operators based on their experience on the process, and hence, may not be precise in control since the process dynamic is changing rapidly. Therefore, this study aims to design an autotuning PID controller for nonlinear exothermic process control. This paper presents Genetic Algorithm PID (GAPID) controller in which PID gains are auto-tuned by GA approach. The performance of this controller is investigated in MATLAB-SIMULINK. From the results, it can be concluded that the GAPID controller able to provide a better control compared to conventional PID controller. 1.0 INTRODUCTION The polymerization of resin adhesives, which is a highly nonlinear process, is chosen for simulation studies in this study. Resin adhesives are produced by mixing phenol and formaldehyde together with the use of catalyst. The mixture has to go through a specific heating process to achieve the good quality of resin. However, when these chemicals are mixed together, a sudden and unpredictable heat is produced due to a nonlinear exothermic reaction [1]. Each time the reactor temperature deviates from the desired temperature, the quality of resin diminishes, the appearance of undesired solid product increases, and the overall performance of the reaction decreases which directly affects the economic performance [2]. Therefore, temperature control plays a decisive role in the production of resin adhesives. The most commonly used strategy in polymer industries to control the process temperature is a PID controller. The PID gains are usually determined by the operators based on their experience and knowledge on the process. Therefore, it is difficult to determine the best values to produce the desired output especially when the time delay of the process is varying within a wide range all the time. Furthermore, as the process dynamic rapidly changes throughout the process, it is very time consuming for the operator to determine suitable values through trial and error method. As a result, the conventional PID controller is less suitable for temperature control of exothermic batch reactors since it is slow and has inherent lack of efficiency in handling nonlinear systems [1]. Therefore, this paper aims to design and develop an auto-tuning PID controller to control the temperature of nonlinear exothermic process.