A Method for Closed-Loop Identification of Plants with Unknown Delay

摘要

This paper proposes a new procedure for the closed-loop parametric identification of a linear plant with an unknown time delay. The plant order need not to be known in advance. The method is based on a generalization of Ziegler-Nichols' (ZN) experiment. As in the standard ZN method, only the plant controller is used for the experiment, and no extra equipment is needed. Moreover, the method does not require sustained undamped oscillations in the plant, since the identification may be accomplished with slightly damped oscillations as well. However, more experimental runs are necessary in that case.