Identification of shift and delta operator models for small sampling periods

The method of identification of the discrete-time (DT) transfer function (TF), for the system composed of sampler, zero-order hold and continuous-time (CT) plant is proposed. The case in which the identification errors result from inaccurate measurements, while the errors resulting from information processing are negligible, is considered. It is assumed that beyond the system input and output an additional intermediate signal (-s), separating the CT plant into some parts, is measured, sampled and used in estimation. The proposed method is based on observation that the separated parts of the CT plant are described by the DT TF-s, which may be identified using available measurements. From simulations performed results show that the identification accuracy of shift and delta operator models, for small sampling periods, is comparable. It is also seen that the proposed method improves the identification accuracy for both these models, significantly