Tension control of web of winder span using adaptive gain control method

One of the most important issues concerning the handling of the web in a roll-to-roll printing system is tension control of the web. In particular, the tension controls for the winders, including both the un-winder and re-winder, are required for the stable supply of the web and collecting of the printed electronic devices in the form of a roll without causing defects in the devices, respectively. The web tension control of the winder span requires time-variable control gains because the dynamics of the web vary with the winder roller radius. If fixed gains are used to control the web tension of the winder span regardless of changes in the radius of the winder roller, the tension could be unstable. Therefore, previous studies have tried to control the web tension of the winder span while considering the time-variable characteristics of the web dynamics by changing proportional-integral-derivative (PID) gains according to the roll radius or by applying adaptive control methods. However, most of these studies were limited to simulations. In this study, different types of fuzzy-PID controllers were applied to control winder tensions considering the dynamic characteristics of winders in a roll-to-roll system. A modified fuzzy-PID method is suggested that adjusts PID gains to correspond to changes in the dynamics of the web of the re-winder. PID gains based on these fuzzy rules vary within a range of positive values according to changes in the unwinder roller radius as opposed to the conventional fuzzy-PID controller, in which the fuzzy rules vary from negative to positive. On the other hand, the conventional fuzzy-PID controller is applied to the re-winder control to improve the response considering dynamics characteristics of re-winder that differs from that of re-winder. The proposed method was applied to the tension controls of the un-winder and re-winder of an actual roll-to-roll system and was verified through experiments. Both the simulation and experimental results showed that the proposed method can successfully control the web tension of winder systems. (C) 2014 The Japan Society of Applied Physics