Liquid Level Control Using a Variable Parameter Fuzzy Controller

Fuzzy Logic provides an innovative control methodology suitable for both linear and non-linear systems. It can be easily implemented in embedded systems and Programmable Logic Controllers (PLCs), leading to lower development costs, enhanced robustness, and practical application in real industrial environments. This paper presents the design and implementation of a Variable Parameter Fuzzy Controller for liquid level control, programmed on a PLC Modicon M580. The performance of the proposed fuzzy controller is compared to that of a nonlinear PID controller using performance indices such as the Integral of Squared Error (ISE), Integral of Absolute Error (IAE), and Integral of Squared Control Output (ISCO). The main contribution of this work is the enhancement of the response of the fuzzy controller through the nonlinear variation of the scaling gains based on the error. Experimental results demonstrate that the proposed controller significantly outperforms the nonlinear PID controller in both liquid level regulation and disturbance rejection tests.