Physical modelling and control of lateral web position for wallpaper making processes

This paper presents a modelling and control algorithm for the lateral movement of web using a pivoting guider, where an accurate lateral positioning is important for web conveyor systems so as to achieve a high productivity and improve the product quality. The process considered is the hot embosser for the polyvinyl chloride-based materials where a steering guide is used for the in-register embossing. A new theoretical model is developed by regarding a moving web as a beam with a very small, but finite thickness. This leads to a transfer function that has four complex poles and two zeros with a time delay. This model has been validated through real experiments. The design of a Smith predictive control scheme has been made that shows, from a number of real-time applications, a high potential in speeding up the response of the pivoting guider and reducing the lateral variations of the moving web.