A frequency based method for complete identification of Hammerstein-type plants based on relay feedback

This paper proposes a new closed loop frequency based method for a parametric identification of Hammerstein type plants. The method is a generalization of Ziegler Nichols´ (ZN) experiment, with relay added in the control loop. It provides a parametric model of the linear part of the plant, and a point by point relationship between input and output of the nonlinear part of the plant. In the paper, such obtained relationship is later used to derive a polynomial parametric model of the input output relationship, although other parametric models may be used too.