A new closed-loop identification method of a hammerstein-type system with a pure time delay

A procedure for the closed-loop identification of a class of Hammerstein type nonlinear plants with a pure time delay in the linear part, based on a generalization of the well-known Ziegler-Nichols´ (ZN) experiment, is proposed. It provides a simultaneous estimation of the linear plant dynamic, input-output approximate model of the nonlinear part and value of the time delay. As in the ZN method, only a suitable controller is needed for experiments. Tuning of PID controller based on the obtained plant model is compared with PID tuning recommended by Ziegler-Nichols method and clear advantage of knowledge of the plant model is demonstrated.