A Simple Identification Technique for Second-Order plus Time-Delay Systems

Second-Order plus Time-Delay (SOPTD) models are commonly used to approximate systems in order to tune PID controllers. Simple models are dominating for control design in industrial applications. Several estimation techniques have been developed and applied to controller design. Most estimation techniques are based on least-squares and excitations such as step, square waves and pseudo-random signals. In order to speed up the experiments, simple and short excitations have also been considered. In this paper alternatives are proposed to robustify the estimates in order to obtain a better model around important frequencies. Simulation results are presented to illustrate the techniques.