THE R-S-T DIGITAL CONTROLLER-DESIGN AND APPLICATIONS

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