Decentralized control strategies for web tension control system

Web tension control systems have a structure of multi-inputs and multi-outputs consisting of many subsystems. Those subsystems are divided into two main groups of systems such as tension control and speed control systems, and have strong interactions between neighboring subsystems through the associated web tensions. The decentralized controller of each control station attached to a subsystem is expected to control the output according to the reference regardless of the interactions. This paper shows some control strategies to compare the performance and to study the decentralized control concept. Two methodologies for designing the controller are presented. One is a high gain adaptive control scheme, and the other is an H-infinity control scheme where a new weighting function is introduced to obtain global stability. From a computer simulation, each benefit for the control strategy is discussed.