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P2V (not plus) Unstable After Crash

Discussion in 'Phantom 2 Vision Help' started by rDp, Oct 2, 2016.

  1. rDp

    rDp

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    P2V fell 403 ft. at a distance of 600 ft. from Home point. Before falling, P2V became unstable and lost signal with RC; flight software was DJI Ultimate Flight. Surprisingly, visible damage was props and prop guards. Landing leg containing compass was slightly compressed with cover pooped off.
    Replaced props & prop guards but P2V couldn't get off the ground; one side was lifting causing the props on the other side to hit the ground. My initial thought was that the IMU needed calibration. Hooked up the P2V to the Assistant hardware and it stated that the IMU was running hot and to shut it down, let it cool off and retry. That wasn't the case since I knew that it was cool, recalibrated. P2V was able to get off the ground but was unstable; drifting in one direction and up and down.
    How do I determine what the problem(s) is? Do I need a new compass? Does the GPS module require replacing? Or, is it a motor(s).
     
  2. Mark The Droner

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    Do all the motors idle correctly?
     
  3. rDp

    rDp

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    All motors seem to idle properly (determined by ear). But there is no guarantee that at higher rpms the electromagnetic fields are weaker. I'm still thinking that it is a drift problem due to the IMU or Compass.
     
  4. Neon Euc

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    Have you tried reinstalling the firmware. A fresh boot may correct any system errors

    Sent from my Power using PhantomPilots mobile app
     
  5. rDp

    rDp

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    Thank you for the assistance I am receiving. I reinstalled the firmware, removed the prop guards, installed new props and calibrated the RC controller. What is happening now is that the P2V is lifting on one side jamming the other side into the ground. facing the camera it is lifting left to right.
    Also, is the P2V suppose to be balanced with or without the battery installed when a finger is place under the arm LEDs adjacent to each other? Mine is not. The leaning is not equal. One side leans further than the other. I never checked before the crash.
    Thanks for your continued assistance.
     
  6. Mark The Droner

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    Sounds like IMU to me. Normally I'd think maybe you just need to give it more thrust on takeoff, but I see you've been on the site over a year so that's probably not the solution. I suggest contacting @J Dot because he's repaired a dozen or more of these P2Vs. He knows more than most of us...
     
  7. J Dot

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    Hello,
    Sorry I'm chiming in late, ( thanks for the alert Mark ).

    rDp,
    There could be several things causing the flip or instability!
    First
    Are all 4 motors level with each other
    ( a motor/arm can tweak in a crash ) causing a motor to become out of level with craft ) usually visual inspection will be enough, but another way to check is to put props on, spin by hand, check measurement from phantom top case to prop tip, then spin prop 180 degrees and measure other top from phantom shell, measurements should be equal! ( on each prop ) also check bolt holes, screw holes can break loose causing motor to be unstable, as shell is just plastic, and can crack or break easily in a crash.
    ( make sure all 4 props are DJI props ) aftermarket props don't have the same lift as OEM DJI props, if they DONT SAY DJI ON THEM, toss them!

    Ok
    If you have craft open, under the top plate is your GPS unit, remove shielding, then remove 4 tiny Phillips screws, visually inspect GPS ( Ceramic antenna for cracks ) as it can crack very easily ) causing faulty or inaccurate GPS readings, or none at all! ( if it looks good, reinstall it, and let's move on )

    While open
    Inspect all connections to naza, and motherboard, scrutinize every connection, wire, solder joint, check closely ( as wires can pull out of those tiny connectors ) or ( solder joints can crack or come loose )

    Ok
    Now we need to check your compass, gyroscope, and accelerometer
    ( compass ) is where you are facing on Magnetic earth ( this is what keeps bird facing one direction )

    ( gyroscope ) is in charge of SPINNING movements ( Yaw )
    And
    ( accelerometer ) is in charge of all straight line movements ( up-down-left-right-fwd-reverse )

    Ok
    This being said the IMU, ( Inertial Measurement Unit ), takes readings from these items, constantly, I'm sure thousands of times per second, but it takes these readings, averages them out to a MODDUS, or Mod value ( MODDUS is another term for Absolute value ), so when you hook phantom to PC ASSISTANT, and under advanced tab, you'll see the MOD values of ( gyroscope, accelerometer, and compass )
    Please let us know these values?
    Gyroscope and accelerometer should Be Very close to 0 ( usually a 1 or .8, something like that and NOT JUMPING AROUND ) should stay pretty stable to whatever number they are.
    Now Compass, you should be in a range of around 750-2400 I believe, but let us know. This will tell us if the compass is working or is whack! You can reset them if mod value is WAY off, requires a strong magnet and some patience!
    ( also check compass connection closely, if cover poped off, connector or wire could be damaged? )

    Now if all looks good
    Hook only Tx to RC ASSISTANT, do a full calibration ( both sticks, both toggles, and dial wheel if avail ( or 7th channel mod if avail )
    This will recalibrate your Tx!
    Next
    Hook phantom to PC ASSISTANT, under basic-RC tab, calibrate Tx here again ( bother sticks, toggles, and dial wheel/7th channel mod ) this will calibrate Tx to bird, so they will be perfectly synced together.

    Lastly
    On a wooden table ( preferably ) do an ADVANVED IMU CALIBRATION ( Must keep bird perfectly level and stable from any movement ) I use a CUBE LEVEL, directly on top of naza unit, most use a piece of thin glass across all 4 motor shafts, level ALL directions, once level perform IMU calibration , after calibration is complete, go outside and do a fresh compass calibration.

    Now what I would do, is PIN DOWN the phantom ( I use 3 two pound dive weights on each leg ) that way I can spoil up motors with props on, and phantom cannot lift off, once pinned down, rev motors all the way up, listen and look for anything weird, loud squeal , pauses in spins, or erratic behavior in any of the motors, and I'd test heat on each motor after 3-5 minutes of running motors up, if any motor temp is more than other 3, you might have a bad motor bearing?
    All motors should be close to same temp usually 80-90 degrees, after 3-5 minutes of running.

    Also check your camera anti-jello balls, if any are torn or cracked, can cause a wobble as well, has happened to me before.

    Once all this is done and everything passes the test, try a flight
    ( make sure props are balanced ) this too can cause unstable flight!

    ( also balancing craft does not matter, naza will correct any unbalanced problems ) as I hang my tracker on one side of my phantom with no issues!

    Hope this helps or at least gets you on the right track!

    J Dot
    :cool:
     
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  8. rDp

    rDp

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    Thank you to everyone for your help. J Dot, I haven't gone through your comprehensive reply yet and will after I get a reply to the following. As Mark the Droner suggested, I recalibrated the IMU with no difference in the flipping scenario. However, when I entered the IMU calibration sequence I got the following alert.
    "Temperature of MC is too high to achieve best effects of calibration. Please power off MC, cool for 5 minutes and then re-do the Advanced Calibration."
    The PV2 had been powered for about 45 seconds and did not have time to get hot. Does anyone think that my problem is the MC (Main Controller}?
     
  9. Mark The Droner

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    My opinion is it's possible, but unlikely. The message you got is pretty common. I've had it before. Lots of people have had it, but it doesn't necessarily mean there's a problem.
     
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  10. J Dot

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    Agreed
    I get it also, I just click and proceed!
    ( might help puting a fan to blow cool air on it while doing cal? )
    ( I put a fan on my plus models when transferring images and video, as wifi has no wind to cool as it sits there! )

    J Dot
    :cool:
     
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  11. crash1sttime

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    If its been dropped from a height I would suggest opening it up and checking the GPS puck, also maybe the Naza has torn loose from the board and isnt sitting level anymore, also the wifi module could have come loose.
     
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