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Leveling the Phantom for calibration

Discussion in 'Phantom 2 Vision + Discussion' started by rexster314, Feb 3, 2015.

  1. rexster314

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    After using business cards, folded paper, flat washers, I came up with this contraption. 5/16" lexan which doesn't flex, 4 7/16" bolts and nuts and some quickset epoxy glue.

    Drilled out each corner with 1/2 drill bit, glued the nuts over the holes, threaded the bolts through the nuts after epoxy dried. As you can see, each corner is adjustable by screwing the bolt in or out using my S5 with a bubble balancer app. So I can level the platform before putting the Phantom on it for calibration no matter where I do it (within reason) then run the and IMU calibration. I can add or subtract each corner if I want to skew the Phantom's attitude.

    Here's some pics (of course)

    [​IMG]
    [​IMG]
    [​IMG]
     
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  2. LostAngel

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    Nice idea. May have to copy that design.
     
  3. flyNfrank

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    That is a nice setup, but I'm guessing that most open people will say that is probably a little over doing it. I'm only being honest, and I may have some that will want to bark about saying such a thing. If you have a level problem then by all means use what you have there, Just remember to stay clear of any type of metal which will mess with your settings. I have calibrated mine from the top of a cardboard box. Now I don't do from the carpet because of the screws used to secure the flooring under it.

    And most importantly, read the info that appears in the Phantom Assistant that shows what the acceptable range for each section for the IMU.

    Gyroscope ~ 0.0 - 1.5
    Acceleration ~ 0.98 - 1.02
    Compass ~ 750 - 2250
    *Note ~~~ Read info for each on what to do should readings come up just below - or just above setting values.
     
  4. rexster314

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    Flynfrank, you certainly have a right to put your comments on here. If I was thin skinned, I wouldn't post anything. I like my set up as it takes all guess work out of finding a level plane in my house. This way I can go anywhere in the house and have a level surface. I'm sure a lot of other people have the same problems or they wouldn't be using business cards, washers, or other types of shims to level their birds out. I used this the other night after playing around with the IMU settings, popped off the top of the P2V2, put it on the leveled surface and put my spirit level on the top of the IMU itself and then recalibrated again. Went flying today and it's never been so tight in yawing the bird except when I first bought it back in first of December. I have to make use of the workbench I constructed several years ago or wife will start using it.
     
  5. cahutch

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    I'd be concerned about those large steel bolts interfering with the compass. My computer desk is level to within 1 degree and I do my IMU calibration there but I make sure I keep anything metal far away or I get a compass error.
    I would look for some aluminum or nylon nuts and bolts.
     
  6. spudmachine

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    Likewise - the steel bolts would make me nervous.

    I found this 10-pack of plastic nuts and bolts for car number plates (translation: license plates in the USA :) ). I assume something similar is available in the USA.

    They would need to be reasonably sturdy to hold on a plate in winds of 70mph or more.

    http://www.ebay.co.uk/itm/Plastic-Numbe ... 0609929373


    Or if you think those would be too short, then here are some nylon nuts and bolts. Nylon is a pretty strong plastic.
    http://www.ebay.co.uk/itm/5mm-x-25mm-NY ... 1288382905
     
  7. crash1sttime

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    Is this just a vision plus issue ?

    I've never had to do any kind of levelling for my Vision.
     
  8. cahutch

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    If you do an IMU calibration it needs to level or very close to it.
    If you calibrate off level, it could fly away unexpectedly.
    When it's in a hover it tries to stay level and compensates for drift with the GPS.
    If what it thinks is level is not actually level, it will be slightly tilted and so will move when it doesn't want to. It can still compensate for drift if it's slow and gradual.
    If level is way off though it will be tilted far enough to move quickly and the gains won't be enough to compensate fast enough.

    Here's an example of an IMU that isn't calibrated to level.
    https://www.youtube.com/watch?v=1TQQcBWV6Vs
    After this DJI updated the firmware to warn you and prevent takeoff if the IMU calibration is off.
    It looks like they are updating the Phantom firmware to do the same thing next revision.
     
  9. max

    max

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    Frank and others, why are you so concerned about have metal near the quad during IMU calibration? The IMU contains the gyroscopes, accelerometers, and barometer. Proximity to metal is not going to effect any of these sensors. The compass is entirely seperate, and as we all know, calibrated separately.
     
  10. Hughie

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    Having said that, the first time I took a plastic and glass spirit level out to do an advanced IMU I noticed some odd compass readings in the assistant.

    It turned out that the spirit level had a sodding magnetic strip running along one edge which I hadnt noticed. I tossed it straight in the bin. :)
     
  11. cahutch

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    Yes, but if you get any metal near the compass while plugged into the software, you get a compass error warning and you can't do anything with the software until you clear the warning.
     
  12. N017RW

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    I've read where people have had a slight drift to one side or another and have attempted to 'counter' this drift by tilting the quad in the opposite direction by as much as a centimeter during IMU cal.

    It made no difference.

    I'm not suggesting that leveling is not necessary, nor have I tried to tilt during cal on purpose to see for myself. I'm just adding some anecdotal information for the group to chew on.
     
  13. crash1sttime

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    Yeah thank for the rather extended post on the reasons why an IMU should be calibrated, maybe if you spent as much time actually reading my question as you took to write out your essay you would have spotted that I asked and I paraphrase "is this just a vision plus issue.

    A simple answer from a non plus owner who has suffered a similar issue would have answered the question.

    Thanks though for the lesson I'm sure someone other than myself may find it informative.

    As for the YouTube video, I've seen it before when someone blamed it on using ground station incorrectly.
     
  14. bobomet

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    Nice design!
     
  15. bobomet

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    Do you folks think this is close enough for an IMU Calibration?

    [​IMG]
     

    Attached Files:

  16. BlackTracer

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    I would say yes. Some may disagree but they are OCD in my opinion. I would think it would fly very well with that level of a surface.
     
  17. alberto hernandez

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    I have been leveling my on a cardboard box doing good I was of better way I thought a board but yours is perfect
     
  18. Illina

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    Lol.....yup. My last IMU calibration was done when I set my Phantom down on the roadside of an old country road with a huge crown in it. That was back in November and been flying it ever since.
     
  19. crash1sttime

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    Nice work, I put a piece of plate glass over the 4 motors and use the exact same spirit level to make sure it's level before doing an IMU cal.


    Sent from my iPhone using PhantomPilots mobile app
     
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  20. dirkclod

    dirkclod Moderator
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    We talking old school there crash .Still do it that way :)
    That thread is way back eh ;)