Design and performance evaluation of fuzzy variable fractional-order [PI]^λ D^μ controller for a class of first-order delay-time systems

This paper presents the design of a fuzzy variable fractional-order PID (FVF[PI]^λ D^μ) controller and its level of performance. The fist-order plus delay-time (FOPDT) pressure control fractional-order plant model is identifid using an experimental dataset and designed for study the control scheme. The conventional integer-order PID (IOPID) controllers' performance is not satisfactory for the systems with nonlinear characteristics, plant uncertainties, and external load disturbances. Thus, a modifid control structure is proposed in which the exponent terms ^λ and ^μ of the controller are changed lively using an intelligent fuzzy logic controller (FLC). To investigate the usefulness of the proposed control method, simulation studies are carried out using MATLAB software. Further on, the proposed controller performance for the identifid fractional-order plant is compared with that of the IOPID and classical fractional-order PID (FOPI^λ D^μ) controllers. The controllers' performance is demonstrated during the parameter change and under external load disturbance conditions. The results confim that the FVF[PI]^λ D^μ controller is capable to achieve an improved performance and robustness for the identifid FOPDT pressure control systems.