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Frontiers of Information Technology & Electronic Engineering >> 2024, Volume 25, Issue 2 doi: 10.1631/FITEE.2300620

Estimation of Hammerstein nonlinear systems with noises using filtering and recursive approaches for industrial control

Affiliation(s): School of Electrical & Information Engineering, Jiangsu University of Technology, Changzhou 213001, China; College of Electrical, Energy and Power Engineering, Yangzhou University, Yangzhou 225127, China; less

Received: 2023-09-13 Accepted: 2024-02-23 Available online: 2024-02-23

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Abstract

This paper discusses a strategy for estimating in the presence of measurement noises for by applying filtering and recursive approaches. The proposed are made up of a (NFN) and a linear state–‍space model. The estimation of parameters for Hammerstein systems can be achieved by employing , which consist of step signals and random signals. First, based on the characteristic that step signals do not excite static nonlinear systems, that is, the intermediate variable of the Hammerstein system is a step signal with different amplitudes from the input, the unknown intermediate variables can be replaced by inputs, solving the problem of unmeasurable intermediate variable information. In the presence of step signals, the parameters of the state‍–‍space model are estimated using the recursive extended least squares (RELS) algorithm. Moreover, to effectively deal with the interference of measurement noises, a technique is introduced, and the filtering-based RELS is formulated for estimating the NFN by employing random signals. Finally, according to the structure of the Hammerstein system, the control system is designed by eliminating the nonlinear block so that the generated system is approximately equivalent to a linear system, and it can then be easily controlled by applying a linear controller. The effectiveness and feasibility of the developed identification and control strategy are demonstrated using two industrial simulation cases.

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