A three-step identification method based on step response and open loop - closed loop transformation

Due to the existence of time delay, model parameters identification in industrial processes has brought certain difficulties. This paper presents a three-step closed-loop identification method based on step response and open loop transformation. Firstly, the entire closed-loop model was identified from the closed-loop input and output data. Then the open loop output data can be obtained through a certain transformation. Finally, an instrumental variable method is applied to identify both the model parameters and time delay. The method proposed can avoid the complexity of the direct closed-loop identification and improve the identification results and accuracy for continuous system with large time delay. Experiment results demonstrate the effectiveness of the proposed method.