Estimating second-order dead time parameters from underdamped process transients

Two simple methods for determining second-order dead time model parameters from underdamped process transients are presented. One of the methods relies on three characteristic points of the oscillatory step response curve. These three points attempt to minimize the integral of absolute error between process and model responses. The other method is based on just two points of the step response. Illustrative examples show that the proposed techniques allow rapid and reliable estimate of parameters.