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Do I need to recalibrate UMI or just compass?

Discussion in 'General Discussion' started by Ezookiel, Mar 16, 2015.

  1. Ezookiel

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    For reasons unrelated to the question, I've had to take off a landing leg with a compass in it, and replace it with a brand new one (I now have a spare white compass leg with apparently the new style compass if anyone wants one). This has meant that I've had to open the shell, disconnect the GPS unit, unplug the existing compass leg, plug in a new compass leg and then re-plug in the GPS, and of course put it all back together again.
    I'm going to redo the compass dance, I'd probably do that as a matter of course after any kind of operation on the machine, but I'm not sure if I also need to recalibrate the UMI after that kind of a change.
    It's not a huge issue if I do have to, but it's just a challenge finding a truly perfectly flat surface to do it on. Certainly difficult in my house, and even more so outside.
    I'm inclined to do it anyway, regardless of the hassle, but would just be interested to know if it's actually necessary, or most likely a waste of my time.

    And if you're interested in why a new leg was needed; when I bought the P2 it was hydrodipped in carbon-fibre-effect. However, the newer compass that DJI had apparently released (or something like that according to the seller) wasn't available yet in the carbon effect leg, so they had to give me the P2 with one plain white leg so it would have the newer compass, and order me in at their expense, a carbon-effect one with the new compass. It only took like 3 months to arrive!!!! But, finally it arrived, and I was able to finally have matching legs (almost matching, the damned thing has a very slightly DIFFERENT carbon-effect pattern, but at least it's ALMOST the same. A plain white one stood out like dog's proverbials). I took off the plain white one - now spare - and put on the almost matching one today. Also the first time I've had the guts to open the shell. Wasn't as scary as I thought it was going to be.
     
  2. N017RW

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    Personally I wound not mess with the IMU. This is not out of fear or paranoia, but it's simply not necessary unless you have moved the Naza or had a crash. Some would also say after a firmware update as well.

    However anytime you, add, remove, or relocate anything to or on the quad Compass compensation is a must!
     
  3. Mako79

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    Me Me Me... I'm looking to upgrade my compass. I have the older non integrated style.

    And in regards to doing Adv IMU calibrations, you only need to do it if the phantom tells you to. This is normally after a hard bump.
    If you decide to do an Adv IMU, find a place that is levelled with the horizon in all axis. Provided that DJI installed the NAZA on a level surface and the skids aren't bent, this will minimise yaw drift. This is where the phantom is unable to spin/yaw in one spot.
    Also, when you do an Adv IMU calibration, make sure the phantom is cool (not flown for an hour). Do the Adv IMU the moment you plug in the phantom. This will prevent the MC heat warning appearing. The colder the phantom, the quicker the Adv IMU is done.
     
  4. ccase39

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    In resp,onse to the part about finding a level surface being a PITA, go to hardware store and buy a level for around $10. Use it to find the most level surface in your house and if it isnt completely level add printer paper a piece or two at a time under the LEVEL until it shows plumb. Now you know its perfectly level. Much faster and more accurate than trial and error.

    If you want to go the extra mile you can shim the surface to make it become completely level. If you have a small table or night stand just shim the bottom until the level is true.
     
  5. N017RW

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    Recently folks have been going as far as determining 'level' at the FC itself (Naza), and then shimming or the like to make the FC coplanar with the motors.

    I have not tried this yet so I can't say how fruitful it really is.
     
  6. dirkclod

    dirkclod Moderator
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    I have started using a piece of glass laid across all 4 motor shafts to get level and then doing advanced calibration and it has helped mine .
    The table I use is level but when I use the glass I had to shim the corners of the skids to show it as level .

    I have never paid that warning no attention as I see it every time I do one . I just click yes and it works fine for me and really has never took but a few minutes for it to complete on Mine .
     
  7. Cyclone

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    Dirk, have you seen an improvement in yawing now you have got it level?

    Also I've done the imu calibration right from turning the Vision on. No warnings come up, they usually do if it's been on a few minutes.
     
  8. dirkclod

    dirkclod Moderator
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    Yes , it tends not to drift off to 1 side like before.
     
  9. Ezookiel

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    Before my first IMU recal' it used to move forward every time I'd try to rotate. That was fixed by the last recal'
    I won't do one this time then unless there's a problem. I'm hoping to test it all this afternoon if the weather holds off.
     
  10. Cyclone

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    Thanks. I put a long spirit level on mine, motor to motor, and skimmed it up slightly. It seems level but not had chance to fly it yet.
     
  11. dirkclod

    dirkclod Moderator
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    If it still drifts get the glass and try. I was surprised what I saw on it as my table was level but not on the shafts with the glass. Now if I can just get that glass back in that picture before the wife see's I swiped it all will be good :D
     
  12. Cyclone

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    :lol:

    I bought a glass chopping board as it was the only flat glass thing I could find. Just have a feeling if I put it on the motors it will squash the Vision :shock:
     
  13. Ezookiel

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    Bloody weather!!
    Get off work, quad in car, and the weather radar says there's rain not far away. It was right. Never got to test the new leg, or anything else with it.
    Every time I actually NEED to fly the damned thing, the weather pours, or blows a gale. Every time I actually CAN'T fly it because of work or commitments, the weather is superb.
    Grrr.... Mutter Mutter, grumble, whinge complain.