Quantitative Analysis on Open-Loop PI Tuning Methods for Liquid Level Control

In the overall operation of a system, the controller plays the most important role in protecting the system from external as well as internal disturbances, faults, or failures. One of the most renowned and simple classical controllers being widely used in many applications is the PI (proportional plus integral) controller. The control system's effectiveness relies on the proper design of PI gain constants. Besides, due to varying operating conditions, it is always required to design suitable PI parameters to obtain a desired response from the system. There are many state-of-the-art methods available for computing PI gains. However, picking the right method with respect to the given system transfer function is always a tough task. In this regard, to select the best method, multiple comparative analysis has to be performed on different existing methods. From the literature, OLTR (open-loop transient response) and EPI (Error performance index) methods are identified as suitable methods for PI gain parameter design. So, this paper gives a detailed quantitative comparison of these methods for the design of PI controller parameters for a given liquid level system transfer function. Various time-domain performance indices are computed to evaluate the efficacy of these methods. The system is implemented using MATLAB/Simulink software.