Vedrines M., Knittel D.

THE systems handling web material such as textile, paper, polymer or metal are very common in the industry. Modeling and control of web handling systems have been studied for several decades mostly without considering moving web vibrations. One of the objectives in such systems is to improve decoupling between web tension and speed, so that constant web tension can be maintained during process speed changes. The system under study is quite common in industry : it is composed of an unwinder, a traction motor, and a winder and presents the inherent difficulties of web transport systems. In web transport systems, roll excentricity and non-circularity create web tension disturbances. Longitudinal moving web vibrations are quasi periodic, due to the change of the wound roll radius. Moreover, out of plane web vibrations can occur. These disturbances may induce web breaks and folds or material damage. This paper focuses firstly on the construction of a non linear plant model based on physical laws, with longitudinal web vibrations. The model is built in Matlab / Simulink software environment and has been validated on a real benchmark. Moreover, out of plane web vibrations have been measured and analysed and the influences of free and forced vibrations have been observed : a web vibration resonance can occur in some cases. Theoretical explanations are given and the important role of out of plane vibrations is pointed out. The second part of the paper deals with the active control of such out of plane vibrations. These vibrations are measured by a laser sensor, and rejected using a new actuator strategy for such plant : a loudspeaker. Different controllers have been studied and experimented on the real plant such as PID controllers and adaptive algorithms based on phase-locked loop.