Objectives: The main objective of this work is to design a relay feedback based PI controller to maintain the level of two tank conical interacting level system (TTCILS) which is highly a non linear process. Methods: This technique is based on the observation that when the output lags behind the input by π radians, the closed loop system can oscillate with a period of Pu. It is a simple way to tune PI controllers that avoids trial and error process. Findings: A continuous cycling of controlled variable is generated from the relay feedback experiment. The important process information, ultimate gain and ultimate period can be extracted directly from the experiment. Model design and simulation is carried out in MATLAB/SIMULINK environment. Conclusion: The advantage of this method is that, it requires a single relay feedback test. Simulation studies prove that this technique has good tracking and disturbance rejection capability.
Keywords: Conical Interacting Level System, Mathematical Model, PI Controller, Relay Auto Tuning (RAT), Simulation Studies