Modeling and H-infinity robust control for winding systems

This paper presents the modeling and the H-infinity robust control for an elastic web transport system including an unwinder, a winder and a traction motor. This model has been created using laws of Physics concerning elasticity, of the web, friction between web and roll, and web speed between two rollers. In this paper, a novel linearization of this model allowed us to predict the relationship between web tension and speed more precisely than previous simplifications.During the winding process the radius and inertia of the rollers change substantially. In order to eliminate system sensitivity to these variations, gain scheduling control was used. In addition, multivariable H-infinity control in our linear model allowed us to effectively decouple web speed and tension. Multivariable control performance was compared with performance of the standard industry decentralized PID control. Results were validated on our experimental webline