The R-S-T digital controller design and applications

The two-degrees-of-freedom R-S-T digital controller is becoming a standard for computer control in industry. This paper presents a methodology for the design of the R-S-T controller, which involves identification of the plant model from data, combined with a robust control design. The performance of the controller can be further enhanced by plant model identification in a closed loop, and re-tuning of the controller. For large parameter variations, adaptation has to be considered in order to maintain the performance. Software packages are available for the design, implementation and commissioning of the R-S-T digital controllers. The methodology is illustrated by its application to the control of deposited zinc in hot-dip galvanizing at SOLLAC (Florange, France). (C) 1998 Elsevier Science Ltd. All rights reserved.