EFFECTIVE DECENTRALIZED TITO PROCESS IDENTIFICATION FROM CLOSED-LOOP STEP RESPONSES

In this paper, a new identification method performed in the time do-main based on the decentralized step-test is proposed for two inputs and two outputs (TITO) processes with significant interactions. In terms of parame-ter identification, the coupled closed-loop TITO system is decoupled to ob-tain four individual single open-loop systems with the same input signal. As in the SISO case, new linear regression equations are derived, from which the parameters of a first- or second-order plus dead-time model can be ob-tained directly. The proposed method outperforms the existing estimation methods for multivariable control systems that use step-test responses. Fur-thermore, the method is robust in the presence of high levels of measure-ment noise. Simulation examples are given to show both effectiveness and practicality of the identification method for a wide range of multivariable processes. The usefulness of the identified method in multivariable process modeling and controller design is demonstrated