Drive requirements for elastic web roll-to-roll systems

This paper analyzes for the first time the influence of the master roller placement of roll-to-roll systems and the effects of velocity and tension bandwidths. In such systems, each motor driven roller is controlled separately (decentralized control). The influence of the master roller position, which is only controlled in velocity and therefore gives the web speed, is studied. The other motor driven rollers are also controlled using optimized PI web tension controllers, automatically synthesized in the fixed-order and structure H∞ framework. The web speed and tension control bandwidths play a major role on the system performances and therefore have to be chosen carefully. The impact of the master roller placement, considering several setting values of speed and control bandwidths, is analyzed with respect to reference tracking, disturbance rejection and robustness to web elasticity variations. Several configurations and settings are compared in time domain simulations and frequency system/signal analysis.