Optimized Tuning of PI Controller for a Spherical Tank Level System Using New Modified Repetitive Control Strategy

–This paper proposes a new tuning method of the PI controller based on New Modified Repetitive Control Strategy (NMRCS) approach. A non linear spherical tank liquid level system is considered here. The NMRC incorporates the idea of Repetitive Control (RC) which accomplishes perfect asymptotic set point tracking. The process dynamics of the level process in spherical tank are described by the differential equation and worst case model parameters are identified by influencing the step test technique. By utilizing relay feedback technique, the periodic reference signal of NMRCS is generated. From the input and output chattering signals of the NMRCS, optimized PI controller parameters are identified using Recursive Least Squares (RLS) fitting technique. Simulation results are endowed to demonstrate the efficiency of the proposed tuning method. A proof of robustness of the NMRCS is also analyzed. Keywords––RLS, ZNTR, MRC, NMRC, Spherical Tank