Relay Identification Analyzing Non-symmetrical Oscillations for Optical Plant

The paper deals with approximation of systems with the dominant first order dynamics by the Integrator Plus Dead Time (IPDT) model based on the analysis of the nonsymmetrical oscillations with possible offset arising typically under relay control. The analytical derivation is illustrated by results achieved by identification of optical plant. The results are experimentally verified by PI controller tuned using the identification results. Process parameters in various operating points are analyzed and the robutst controller tuning based on performance portrait analysis is employed.