Abstract
This paper presents a practical identification method of the linear part of a plant which has nonlinearity in its input. A Hammerstein-type model is used for the plant model and only the linear dynamic part is identified independently of the input nonlinear element by restricting the manipulated variable to take only two values during the identification experiment. The identification signals are generated using a kind of limit cycle test modified to produce fractional harmonic components in the signals. A second order lag plus an all-pass filter is used for the linear model and its parameters are calculated to fit the model frequency responses to the ones obtained by the limit cycle test at two frequencies. A numerical example is presented and adequateness of the model structure is discussed.
