On the Identification of Stable, Integrating, and Unstable Processes with Unknown Orders and Delays

Abstract

This article addresses the complete identification of stable, integrating, and unstable processes. Despite the stability of the process, a biased relay experiment can be performed to provide abundant process input-output data in stable operation. Based on a time-weighted integral filter, an effective method is developed to estimate the orders and time delay as well as the model parameters from the relay-induced data in a straightforward fashion. The method utilizes a small amount of experimental data and is robust with respect to measurement noise and model structure mismatch. Furthermore, it can easily be applied as a model reduction technique by estimating an apparent delay with user-specified orders.