Lighthouse Yaw Offset

Discussions related to positioning systems where the position is calculated outside the Crazyflie and sent to the device using radio, including MoCap systems
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HAW_IxD
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Lighthouse Yaw Offset

Post by HAW_IxD » Tue Dec 03, 2019 3:18 pm

Hello,

two of our lighthouse decks now have a yaw offset (no matter which drone they are on). Is there a way to correct this?

Thank you in advance

Sven



arnaud
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Re: Lighthouse Yaw Offset

Post by arnaud » Wed Dec 04, 2019 7:30 am

Hi,

The only things I can think about is if not all the sensors on the deck are working. Are you running the latest version of the Crazyflie firmware? (there has been a lighthouse deck update a while ago that fixed a sensor initialization bug).

What is the magnitude of the offset?

HAW_IxD
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Re: Lighthouse Yaw Offset

Post by HAW_IxD » Wed Dec 04, 2019 12:16 pm

Hi,

Thanks for the quick answer. Yes, the firmware is up to date. The deviation is about 30°and 20°.

kristoffer
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Re: Lighthouse Yaw Offset

Post by kristoffer » Thu Dec 05, 2019 9:08 am

I don't have a good explanation for this, and I would really like to understand what is happening.
Would it be possible for you to shoot a short video with one working deck and one with the yaw offset? Just a short sequence of taking off, hovering for a few seconds and land.

HAW_IxD
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Re: Lighthouse Yaw Offset

Post by HAW_IxD » Thu Dec 05, 2019 12:07 pm

Hi,
here a screenshot and two videos. To land the drone with the Lighthouse Deck with the offset does not work, because the drone loses its orientation completely with time.
YawOffset.PNG
Yaw Offset:
https://vimeo.com/377527011

Correct Yaw
https://vimeo.com/377527237

kristoffer
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Re: Lighthouse Yaw Offset

Post by kristoffer » Mon Dec 09, 2019 1:54 pm

Thanks for the videos!

It definitely looks weird. I looked at the code for the yaw estimation and it seems as we are not checking that we get valid data from all sensors, I think this could give the results in the video if one sensor is not working.
If this theory is correct it should be possible to detect by looking at the angle logs for the sensors, I would expect some angles to not change when moving the Crazyflie around in space.

There are 16 log variables , one for the horizontal and vertical sweep angles, for each sensor, for each basestation.
It should be enough to log for one basestation and one sweep direction though. Please set up logs and plot for
lighthouse.angle0x
lighthouse.angle0x_1
lighthouse.angle0x_2
lighthouse.angle0x_3
and check if they all change when moving around.

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