Control of roll-to-roll systems with ultra-low tension profile
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 h...
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Format: | Final Year Project |
Language: | English |
Published: |
2017
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Online Access: | http://hdl.handle.net/10356/72210 |
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Institution: | Nanyang Technological University |
Language: | English |
Summary: | 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. |
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