Preliminary process information and its use in OBF-TD model estimation

Abstract

Preliminary process information is generally based on step tests or on operator experience. Step tests are usually long, poorly informative and sensitive to disturbances during the experiment. A preliminary identification test and the time and the frequency identification techniques are presented in order to obtain the preliminary process information. A combined process model, an OBF model part and a time delay part, named orthonormal basis filter plus time delay (OBF-TD) is proposed. As the time delay is handled separately, the model order can be chosen to improve model performance. In addition to that, it is possible to directly obtain FOPTD models. Simulation results for SISO and MIMO processes are presented to illustrate the techniques.