Apriltag and accurate rotation measurement

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batu
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Joined: Thu Oct 10, 2019 2:34 am

Apriltag and accurate rotation measurement

Postby batu » Thu Oct 10, 2019 4:23 am

Apriltag tag25_09 is used for rotation measurement. I have tag size constraint. Can't use tag size bigger than 6cm.
So rotation angles are quite fluctuate and noisy.
How can I improve the rotation angle accuracy in such situation?
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kwagyeman
Posts: 3335
Joined: Sun May 24, 2015 2:10 pm

Re: Apriltag and accurate rotation measurement

Postby kwagyeman » Thu Oct 10, 2019 11:11 am

You should filter the rotation angle input. After detecting a tag once you should be able to track it and filter the rotation angle by expecting movement to follow a certain profile.

Also, increase the camera exposure and decrease AGC, this makes the image more stable.
Nyamekye,
batu
Posts: 3
Joined: Thu Oct 10, 2019 2:34 am

Re: Apriltag and accurate rotation measurement

Postby batu » Fri Oct 11, 2019 1:07 am

Thanks for the reply.
Say the expected rotation angle is 20deg.
But it is varying in quite wide range.
So you mean I need to take most frequent data?
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kwagyeman
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Re: Apriltag and accurate rotation measurement

Postby kwagyeman » Fri Oct 11, 2019 1:52 am

What the quality of the lock? Like, how many pixels can it see. The algorithm needs a lot of pixels of the tag for a good measurement.
Nyamekye,
batu
Posts: 3
Joined: Thu Oct 10, 2019 2:34 am

Re: Apriltag and accurate rotation measurement

Postby batu » Tue Oct 15, 2019 5:24 am

yeah you are right. When the distance is far a lot fluctuation and get closer, quite ok.
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kwagyeman
Posts: 3335
Joined: Sun May 24, 2015 2:10 pm

Re: Apriltag and accurate rotation measurement

Postby kwagyeman » Tue Oct 15, 2019 2:55 pm

We have a new camera with dram coming soon that can do VGA AprilTags and above. The frame rate isn't high but it works.
Nyamekye,

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