Design and Performance Evaluation of Fuzzy Variable Fractional-Order [PI]λDµ Controller for a Class of First-Order Delay-Time Systems

This paper presents the design of a fuzzy variable fractional-order PID (FVF[PI]λDμ) controller and its level of performance. The first-order plus delay-time (FOPDT) pressure control fractional-order plant model is identified 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 modified 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 identified fractional-order plant is compared with that of the IOPID and classical fractional-order PID (FOPIλDμ) controllers. The controllers’ performance is demonstrated during the parameter change and under external load disturbance conditions. The results confirm that the FVF[PI]λDμ controller is capable to achieve an improved performance and robustness for the identified FOPDT pressure control systems.