Identification of Unstable Second-order Transfer Function Model with a Zero by Optimization Method

Abstract

A technique is presented is to identify a transfer function of an unstable second-order plus time delay (SOPTD) with a zero. An optimization method is used to estimate the model parameters to match the closed loop responses. A method is given for the initial guess values of the model parameters (time delay, steady state gain and the values of poles and zero). The method is applied to three simulation examples. The presented method gives good results. The measurement noise and disturbance effects on the model identification are also reported.