On the Identification of Hammerstein Systems Having Saturation-like Functions with Positive Slopes

Article type: Research Article

Authors: Pupeikis, Rimantas

Affiliations: Institute of Mathematics and Informatics, Akademijos 4, 08663 Vilnius, Lithuania, e-mail: pupeikis@ktl.mii.lt

Abstract: The aim of the given paper is the development of an approach for parametric identification of Hammerstein systems with piecewise linear nonlinearities, i.e., when the saturation-like function with unknown slopes is followed by a linear part with unknown parameters. It is shown here that by a simple input data rearrangement and by a following data partition the problem of identification of a nonlinear Hammerstein system could be reduced to the linear parametric estimation problem. Afterwards, estimates of the unknown parameters of linear regression models are calculated by processing respective particles of input-output data. A technique based on ordinary least squares is proposed here for the estimation of parameters of linear and nonlinear parts of the Hammerstein system, including the unknown threshold of the piecewise nonlinearity, too. The results of numerical simulation and identification obtained by processing observations of input-output signals of a discrete-time Hammerstein system with a piecewise nonlinearity with positive slopes by computer are given.

Keywords: nonlinear systems, system identification, Hammerstein systems, parameter estimation

Journal: Informatica, vol. 17, no. 1, pp. 55-68, 2006