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Professional Several P3 Pro Problems

Discussion in 'Phantom 3 Help' started by BobMcKinlay, Jun 6, 2016.

  1. BobMcKinlay

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    So, I've been having a few problems lately. I've tried farting around with different things to see if I can resolve them without luck. I'd appreciate any suggestions or advice.

    Background
    I've had my P3P for about 2 months. Many dozens of flights & 30+ hours logged. I did have a crash about a month ago and sent it in for DJI Care repair. It came back and now I've had the following problems. I'm frankly not sure if some of them are just noticeable now that I'm slightly more experienced or if they've only cropped up since the unit was returned from repair. I will say that I suspect they gave me a new-to-me unit as opposed to repairing my original. Not sure though.

    • P3P -- 1.8.80
    • RC -- 1.6.0
    • DJI Go App - ios 2.8.3 although these problems existing on 2.8.2 as well.
    • All my problems are in calm conditions (certainly less than 10MPH wind, most often near zero).
    • I've done IMU, compass (only once after return from DJI Care), RC and gimbal calibrations a few times. No errors reported; no apparent effect on problems.
    • 90% of my flying is with DJI Go although I'll use Litchi & Autopilot occasionally. Problems exist in all three. When in DJI Go, I am always in P-GPS mode.
    • I'm always flying in the same 2-3 locations. Wide open for thousands of feet in any direction.
    As of now I've resorted to 100% reset-to-default settings on aircraft & RC. No impact on any of these. My gut tells me to send it back to DJI, but I'm dreading that.

    Problem #1
    The good old horizon tilt. I adjust it after takeoff but it will slowly reappear during the course of a 10 min flight or so. Frustrating. Pretty sure this wasn't there pre-DJI Care, but I honestly can't say.

    Problem #2
    On two occasions the gimbal has gone batshit crazy immediately after takeoff with actions awfully similar to the first 15 seconds of the video in this thread. I've reset all the settings via DJI Go after the first incident and it happened again. This is two occurrences out of dozens of takeoffs since returned from DJI Care. In both occasions I landed the aircraft, turned it & RC off and restarted. Everything fine for remainder of session.

    Problem #3
    The P-GPS stability when hovering is simply atrocious. Again, this is in dead calm conditions. The aircraft will "bounce around" five feet on any axis whilst hovering. I always have 14+ satellites and usually 16-17. This most definitely did not happen pre-DJI Care. Another P3 pilot saw it doing this and said it looked to him like the thing was going to flyaway, then changed it's mind. Repeatedly. I can always easily enough bring it home, but it's unnerving how unstable it is.

    Problem #4
    This certainly did not happen pre-DJI Care and I suspect is related to #3. The near-ground (ie. 2-3 feet) performance is horrific. Up/down, all around. I'm scared to land so I've resorted to hand catching which can be challenging because of #3. At first I though it was because the VPS was having trouble determining altitude since I was landing in wavering, but not tall, grass. I don't think this is the case. I've taken to landing on a flat grey rubber mat which, I assume, VPS can get a fix on. Landing is an adventure every time now. I have gimbal guard that I thought was interfering with VPS, so I took it off. No change.

    Problem #5
    Aircraft yaw will not hold steady. Calm conditions. Move forward. Yaw left slightly/softly (w/left stick) and release. Aircraft will slightly, but immediately yaw part way back to the right. The net effect is that if I want to change direction whilst flying forward I need to keep an ever so slight left yaw pressure on the left stick to hold that new direction. Aircraft will also "drift" when not even touching the left stick. Simply give it forward right stick and don't touch the left. After a few hundred yards of travel, the aircraft could be 10-20 yards, maybe more, off the center line of it's direction of travel. This one is the most annoying as it's making it impossible for me to get good video as I'm constantly dicking around with the yaw.

    Any thoughts? Thanks!
     
    #1 BobMcKinlay, Jun 6, 2016
    Last edited: Jun 6, 2016
  2. msinger

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    Turn off VPS in the DJI GO app and you will know right away if it's causing this issue.

    Try calibrating the IMU on a completely level surface. Yes -- that means you should break out your level and check it ;)
     
  3. BobMcKinlay

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    Done and done. No joy.

    I've tried all combinations of VPS on/off, gimbal guard on/off and landing surface grass/mat. Once it gets within 2-3' of the ground it goes into seizures that would make a balloon man on a windy day proud.

    I've always calibrated on a perfectly level table (as confirmed by two levels and the compass app on my phone which we all know is as accurate as they come).

    Actually, the other variable I forgot about is that, post-DJI Care, I'm now flying with official DJO Carbon Fiber 9450's. They are balanced true (I've checked a few times). I'll put on a set of the stock plastic ones and see what that does. Not hopeful.
     
  4. Mako79

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    All your symptoms are IMU related.
    Keep your phantom in a really cool place and make sure you haven't powered it up for an hour or so. Have your Smartdevice on the ready and make sure the Phantom is on a levelled surface in all axis (use bubble levels or a bullseye level). The moment you turn on your phantom, find the IMU calibration screen and do it immediately. The longer you leave the phantom on, the less accurate the IMU will be. You need to remember that the sensors for gyro, acceleration and barometrics is no bigger than a 5 cent coin. This means little environmental changes can have massive affects if the calibration isn't done correctly.
     
  5. Multicoptertec

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    Any chance you could try a different RC?


    Sent from my iPhone using PhantomPilots mobile app
     
  6. BobMcKinlay

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    No access to a different RC. And I tried doing a cold IMU calibration. No joy.

    My son had an interesting observation which I had not noticed. Since 2.8.3 (I think, I certainly never noticed it before), the "distance to RC/VPS height" graphic at the bottom of DJI Go (immediately to the right of the altitude & distance) constantly switches between the two modes "distance to RC" and "VPS height" and always shows the wrong values. Hmmmm????

    Example - last night we were at 300'+ altitude and within 100' of the RC. It showed a VPS altitude of < 10' and a distance to RC of > 2000'. The next cycle (each value displayed for a second or so) showed different, equally wildly incorrect values. No gimbal guard in place.

    Not sure what to make of that.
     
  7. FFPM03

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    I'm experiencing problems 3-5 with my P3A also. No crashes it just started doing it on its own. I've tried to recalibrate the IMU and compass multiple times with no success. It doesn't quite do the "toilet bowling" but it definitely jerks around like it's not sure what to do when hovering. When you recalibrate the IMU are all the values supposed to reset to 0? My X, Y, and acceleration(g) do not show 0 when done. Usually - 1.04 for x and same for Mod. Any ideas? It's only got a handful of flights and I've only had it 3 weeks but it's driving me crazy.
     
  8. John Decker

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    Whs versions were you on prior to sending your bird to DJI? Did they upgrade the firmware?
     
  9. BobMcKinlay

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    No, they didn't upgrade the FW as part of the DJI Care service. My P3P is on 1.8.80.

    So, I've been unable to fly for the last week or so. Until last night...

    Prior to flying, I recalibrated the gimbal and cold IMU. Both processes completed without error. The IMU sensor values are now --

    Gyro - x=-0.00, y=0.00, z=0.00, Mod=0.00
    Acceleration - x=-0.00, y=-0.00, z=-1.00, Mod=1.00
    Compass - x=134.00, y=397.00, z=1746.00, Mod=1765.65


    The results? Exactly the same problems as described in my original message. Stumped and frustrated.
     
  10. Great_Lakes

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    I have nothing to add except maybe upgrade to 1.9.6 on the aircraft.
     
  11. BobMcKinlay

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    On my agenda soon. I can't do much flying in the next week and figured to just let everyone else test 1.9.6 for me. If it's looking stable come next week, I'll go ahead and update.
     
  12. Great_Lakes

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    I've been flying with 1.9.6 for a few days and all seems well so far.
     
  13. John Decker

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    Shouldn't the compass value be around 1500?
     
  14. hunch

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    ok i read this whole thread and no one suggested calibrating sticks on the controller yet.
    try that please and report back.
    hani