Autotuning IMC structure with two-degree of freedom for long time-delay process

In terms of double-controller design technology and relay feedback identification method an autotuning IMC structure with two degree of freedom (TDF-IMC) is proposed in this paper. The model parameters of the controlled process are identified via a modified relay feedback identification method. The setpoint tracking IMC controller and disturbance attenuation IMC controller are designed, respectively, according to the resulting model. At the same time, the autotuning rules for TDF-IMC controller filtering time constant are also given in this paper. The presented TDF-IMC structure improves the performance and robustness of the conventional IMC structure evidently. Moreover, its design procedure is similar and simple as that of the conventional IMC structure.