Tension ripple-free dancer control of a web processing machine

Maintaining web tension in web processing line under changing web speed is a key factor in achieving good final product quality. Tension control systems with dancers play an integral role in such applications. A dancer roll system is essentially a preloaded idler arm with two machine tasks: imposing the web tension and acting as a controlling mechanism to avoid web damage caused by a range of mechanical issues like eccentric and non-circular web rolls or dynamic web speed trajectories. All the dancer control strategies described in literature have one thing in common: they do not adapt their control parameters to the type of web material. The characteristics of the web are not known in advance, and can vary from roll to roll and from time to time. Identification of the web parameters allows more advanced control. In this paper, a digital twin based feed forward controller is proposed to control the dancer in order to obtain variation-free even under varying web speed.