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PVPV3 Height Issues

Discussion in 'Phantom 2 Vision + Discussion' started by rwskinner, Dec 5, 2014.

  1. rwskinner

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    Hello to all. I'm a new quad user and this is my first post. I'm having fun with my V+ and I've flown for about a week now crash free (famous last words).
    Anyways, I've notice since I received my quad, the elevation is off allot. Sitting on the ground it's anywhere from 20 to 60 feet.

    I have upgraded all the firmware and did the RC calibration and I did the joystick cal in the Assistant sw. I then performed the basic and advance calibration even though is said I didn't need to. I have performed several compass calibrations in a nice open area with no change. I have > 10 sats in view and all green lights before taking off.

    Okay, a few feet would not bug me, but when using ground station or return to home, this can be dangerous as return to home is set for 80 feet and it was only off the ground about 20-30 feet. I almost ate a tree. So I fudged it and raised the RTH much higher than it should be for safety.

    Now I'm doing simple way points in ground station and I notice the V+ almost gets to the waypoint and stops for a few seconds then proceeds on to the first WP. Then it does several circles and does some weird things before proceeding to the next WP. Same on each one. The altitude sure doesn't seem right on this either and I have to enter high offsets.

    Any ideas on what I need to do or check? Help is appreciated, and I surely hate to send my new bird off for 4-6 weeks of repair.

    Thanks,
    Richard
     
  2. rwskinner

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    Sorry, I forgot to mention that home position and the remote control position seems to be accurate, and the compass heading on the bird seems to point in the proper position and is steady. I'm using dynamic home thinking it may be safer than setting it once since it updates every couple of seconds.

    Richard
     
  3. mmackinnon123

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    I have the exact same issue

    I am consistently off between 40-60 feet in alt no matter what i do. This is a significant height! I dont want to be at 240 feet to avoid the trees when none of the reach more than about 150 but im afraid to even go 200 cause it might drop to 140 and smack one between way points.

    Seems a little odd.
     
  4. flyNfrank

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    Calibrate your compass guys.
     
  5. phantomi

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    Did you try an IMU calibration? Nothing to loose.
     
  6. eyecon82

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    what this guy said

    I calibrate my compass after every battery change......it's a good habit to have and over 500 flights with not even a suspicion of a fly away
     
  7. Meta4

    Meta4 Moderator
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    Compass? For height issues??
    Can you explain the reasoning for that?
     
  8. rwskinner

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    Compass calibration seems to make no difference. I did the basic and the advanced IMU calibration even though it said I did not need it.
    Seems to be a barometer issue possibly but you would think the 3D gps would also account for the height. My personal GPS is pretty much on the money (+/- a couple of feet).

    Let me ask, I did not fool with the mounting location at all. It is at the factory default with all zero's. Should that be configured or left alone? I figured it was for Naza-M controllers bought and installed in other air frames.

    Richard
     
  9. hionbusa

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    The vision + v3 has an excellent compass and doesnt need constant recalibration...
    I calibrated mine once and it still holds like a champ.

    Your altitude reading is due to changes in barometric pressure.. All phantoms have a barometer in the IMU...

    IMU calibration and update to the latest IMU on the assistant. There is a new update as of last week ..

    Even real planes have to adjust their altimeter readings due to pressure changes .


    https://www.google.com/url?sa=t&source= ... UqXkTe7bfg
     
  10. rwskinner

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    I did the advanced IMU calibration again and this time it took maybe 5 minutes or more where as it usually only took about a minute previously.
    When it was done, I was still at 60' but I power cycled it all and now it is showing 0.5' but as it sits there it slowly climbs. In 2 minutes it's slowly climbed to 4.6' then a minute later at 6.2 feet. That is much better than 60' but for now I will have to keep a close eye on it. If it keeps climbing then It acts like trash in the vent of the baro pressure sensor or a defective baro pressure sensor.

    10 Minutes now and it has sort of stabilized around 4.5 feet so I'm going to call it good for now.

    One tip mentioned was above when Advanced calibration puts a check mark up and the progress bar clears, it's not finished yet, the progress bar will start again and it seems best just to keep a close eye on it because DJI's status bar and check mark is not accurate!

    Thanks for the help,
    Richard
     
  11. rwskinner

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    That was short lived because it was up to 27 feet this afternoon went I went out to fly.
    Any other ideas?

    Richard
     
  12. CYeutter

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    I have not had this problem personally but I remember reading in a similar thread about inconsistent height readings that, similar to what you mentioned, one person found that when he first powered his bird on, he got bad readings but if he power cycled it the reading was much better afterwards. It would be a pain if you had to do that each time but maybe better than flying into things on a RTH.
     
  13. rwskinner

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    Seems temperature related. If I power up cold, the altitude slowly climbs and if I let it warm up real good and power cycle it seems to hold better, but I'm talking like 5 to 10 minutes warm up. I guess I better see about sending it in.