Modeling and Matching Design of a Tension Controller using Pendulum Dancer in Roll-to-roll Systems

Dancer systems are typical equipment for attenuation of tension disturbances. The two kinds of dancer, active dancer and passive dancer, are distinguished by an external actuator. In the active dancer, the position of the dancer roll is measured and the roll is forced by the external actuator to regulate tension disturbances. However, the passive dancer, composed of a spring, damper and roll has no external actuator. Tension disturbance generates movements of the roll of the passive dancer and the displacements regulate the tension variation. However, the hybrid dancer, which is a mixture of passive and active dancer, is applied for the roll-to-roll systems. It regulates tension disturbances indirectly in the manner of keeping a constant position for the roll by changing the velocity of the driven roller adjacent to the dancer roll. It has different characteristics from those of the passive or active dancer. In this paper, the modeling of the pendulum dancer is derived. The dynamics of the hybrid dancer, which feedbacks the position of the dancer roll, and the PI control of a driven roll are analyzed. The matching logic for tuning gains is developed and experimentally verified.