A new relay feedback scheme for identification of non-minimum phase processes with time delay

Abstract

In this paper, attempt is made to explore real time plant modelling based on asymmetrical relay feedback test with step input as an excitation signal. The simulated and experimental investigations result in a set of modified analytical expressions for identification of stable first order plus dead time, non-minimum phase first order plus dead time and over-damped non-minimum phase second order plus dead time processes. These expressions are further utilized for identification of processes in presence of measurement noise using curve fitting tool. Well known examples from literature are included for validation of proposed modelling and identification scheme. Yokogawa distributed control system centum CS3000 with field instruments are utilized for conducting real time experiment on level control system.