Control of roll-to-roll systems with ultra-low tension profile
Date of Issue2017
School of Mechanical and Aerospace Engineering
A*STAR Singapore Institute of Manufacturing Technology
The roll-to -roll web handling machines have been widely used in the printing industries in decades. It involves the transport of thin, flexible, continuous materials called webs, through prints units where the required pattern is printed on the materials. Processing materials in the form of web has the advantages of flexibility, webs can be rolled to the shape of cylindrical shaft for supply and storage. Alternatively, the material would be cut into smaller sections or large manufacturing facilities would be required. The objective and scope of this project is to understand the control architecture of the existing 300mm machine and to optimize the lateral performance in order to prepare the system to carry out the following experiment. Then to study the linearized model of speed and tension control in the machine direction, and tune the controller according to the model-parameters and tension/speed requirements. For the initial setup of the system, telescoping problem occur during winding process due to the wrong placement of ultrasonic sensor and poor web material setup at rewinder roller. The graphical user interface (GUI) for the front panel of LabVIEW is filled with cluttered icons and not userfriendly for controlling the system. Speed uniformity and tension uniformity is hard to achieve due to the disturbances caused by torque ripple of the driving motors and eccentricity of center of gravity on the roller materials, and manual tuning is implemented by try and error where systematic method of finding controller parameters has not been developed. Hence, in order to solve these issues, the telescoping problem is solved first by replacing the ultrasonic sensor and improving the web material setup at the rewinder roller. The GUI is redesigned based on several criteria to perform the tasks efficiently. Control schemes such as proportional-integral-derivative (PID) controller and feedforward control are studied in order to achieve speed uniformity. Then non-convex optimization method is used to optimize the PI controller parameters. In conclusion, this report shows the method to improve the lateral performance of the system, presents a better GUI design, and implements PI and feedforward controller to achieve a high-speed uniformity for the module 2 of the roll-to-roll (R2R) system. This speed uniformity prevents sudden changed in web speed in the print zone during processing, which may affect resolution, registration, and thickness of the printed lines. PI parameters are fine-tuned on module 2 using non-convex optimization method which are speculated for the system to reject high frequency disturbances. And variable gain tuning method is developed for module 1 and module 3 to achieve a higher speed uniformity rather than fixed gain method. Further improvements including application of feedforward control to control the tension in order to compensate for tension transfer from the upstream roller.
DRNTU::Engineering::Electrical and electronic engineering::Control and instrumentation::Control engineering
Final Year Project (FYP)
Nanyang Technological University