Decentralized vs. model predictive control of an industrial glass tube manufacturing process

For the glass tube manufacturing process considered in this paper, one of the controlled variables can only be measured after a considerable time delay. For this process a decentralized (diagonal) PI-controller is compared to a dynamic matrix control (DMC) scheme. The DMC controller shows superior performance in set-point tracking. However, its disturbance rejection properties are comparable. By analyzing the DMC scheme in state-space form, it is shown that the time delay limits the achievable performance of the DMC controller regardless of its tuning parameters. To overcome this limitation, at least partly, it is suggested to use a suitable disturbance model.