Performances Evaluation and Comparison of PID Controller and Fuzzy Logic Controller for Process Liquid Level Control

摘要

Tank level control systems can be found everywhere. It is essential for control systems engineers to understand how tank control system work and how the level control problems are solved. In industrial control systems the liquid level is carrying its significance as the control action for level control in tanks containing different chemicals or mixtures is essential for further control linking set points. All the real systems exhibits non-linear nature, conventional controllers are not always able to provide good and accurate results. Fuzzy Logic Control is used to obtain better response. Fuzzy Logic is a paradigm for an alternative design methodology, which can be applied in developing both linear and non-linear systems for embedded control. By using fuzzy logic, designers can realize lower development costs, superior features, and better end product performance. One of the successful applications that used fuzzy control is tank liquid level control. In this paper, we take the liquid level water tank, and use MATLAB to design a Fuzzy Control. Then we analyze the control effect and compare it with the effect of PID controller. As a result of comparison, Fuzzy Control is superior to PID control. Especially it can give more attention to various parameters, such as the time of response, the error in steady state and overshoot. Comparison of the resultant control response from these two systems indicated that the fuzzy logic controller significantly reduced overshoot and steady state error.