Rule base modification scheme for improved performance of FOPDT process using PI like fuzzy controller

Rule base plays the key role in performance of fuzzy control systems. The performance of the system is affected if a delay element is present in the system. This paper presents rule base modification scheme based on the time delay element in the system. The proposed method is tested on different first order plus delay time process (FOPDT) models using modified rule bases. A criterion has been developed for modification of fuzzy rule base depending on delay time and time constant of the process and is given in tabulated form. The graphical results are given to show the improved process performance using proposed method. Robustness of the proposed method is checked by applying disturbance and setpoint change at certain interval. Comparison with the existing methods is given using performance indices integral of square error (ISE), integral of absolute error (IAE) and integral of time absolute error (ITAE).