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Tracking plastic line
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Tracking plastic line

by rhartl on Sat Aug 03, 2019 4:14 pm

I need a device that will track the rotation and linear position of a plastic line between 1 and 2 mm in diameter. Anyone with an idea for how to do this? Thanks.

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Re: Tracking plastic line

by franklin97355 on Sat Aug 03, 2019 4:37 pm

Can you explain in more detail what you need to track? Rotation?

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Re: Tracking plastic line

by rhartl on Sun Aug 04, 2019 9:10 am

Think of a plastic tube advanced, retracted and rotated by a person manipulating the tube.

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Re: Tracking plastic line

by franklin97355 on Sun Aug 04, 2019 1:28 pm

You might look at using an old ball mouse that rides on the surface of the tube.

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Re: Tracking plastic line

by rhartl on Mon Aug 05, 2019 10:16 am

Any way to do it optically without mechanical contact? I’ve tried the mouse/ tacking ball with kind of limited success.

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Re: Tracking plastic line

by franklin97355 on Mon Aug 05, 2019 12:24 pm

You could try an optical mouse. Other than that the only other thing I can think of is using machine vision but I have no ideas on how to implement that.

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Re: Tracking plastic line

by adafruit_support_bill on Mon Aug 05, 2019 12:58 pm

Rotation around what axis? If there is sufficient contrast between the tube and its background, machine vision could be an option - unless you are referring to rotation around the longitudinal axis.

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Re: Tracking plastic line

by rhartl on Mon Aug 05, 2019 4:37 pm

Yes that is what I am talking about, rotation of the longitudinal axis. I haven ‘t been able to figure it out. Thought you guys might have some suggestions. Thanks for your consideration.

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Re: Tracking plastic line

by adafruit_support_bill on Mon Aug 05, 2019 5:20 pm

Rotating a tube around its longitudinal axis does not change its profile relative to the background. So a machine vision system would not be able to detect the rotation unless there were some sort of encoder markings on the outside of the tube. But a 1 or 2mm cylinder does not present a lot of surface area for any markings.

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Re: Tracking plastic line

by Disciple on Tue Aug 06, 2019 1:08 am

Maybe by using some paints in primary colors, part of the tube could be painted with the colors of the color wheel round about. Then a color vision system might be able to detect the average hue of the visible portion and compute its rotation from that? Just brainstorming.

Hallelujah!
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