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Professional Tilted horizon

Discussion in 'Phantom 3 Help' started by dkyacht, Aug 17, 2015.

  1. dkyacht

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    Ok so I've seen a few threads on here related to this. I didn't want to hijack them so I'm starting this one. I've seen the pics pointing at a set screw that most seem to say is the fix, but I'll be damed if I can see it..... Here's a sample photo just to show which way it's tilted. Before anyone suggests it I'm on the latest firmware and have successfully calibrated my p3p. No crashes or hard landings, just tipped over once when landing on a uneven surface. Not violent at all just messed up the blades on the road, camera never touched anything.[​IMG]

    Dave
     
  2. Oso

    Oso

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    Hi Dave. I suffer from the tilted horizon, so I try to read all threads on the topic. From what I recall, the set screw fix is for people who see their cameras pointing to the left or to the right.

    Your horizon looks like mine at times, but the angle of mine changes as I rotate (yaw) around 360 degrees. It will slowly change from tilted one way, to level, to tilted the other way, to level, etc.

    I'll assume that you have already done an IMU calibration on a level surface and then a gimbal calibration.

    If yours is constantly at the same slanted angle, you could have a mechanical issue. You may be able to correct for it using the gimbal roll adjustment in the app. The latest version of the app has finally made it so that the setting remains. Before the latest app, people had to enter it over and over again even though it may be the same value. Now it's sticky which is much better. This might work for you like I said if your slant is constant.

    Some with a constant slant have even tried to open their gimbals and make a physical adjustment while following a YouTube video. I haven't done this since mine is not mechanical, but if you're brave you could try it.

    If your slant varies like mine does as you fly and rotate, well then I don't think there is one single fix that corrects for it. It seems however that most people who don't suffer from the issue are convinced we are not doing correct IMU and gimbal calibrations (cold or otherwise), are not trying mid air calibrating, or that we must have a hardware problem. They also think we can simply use the gimbal roll adjustment and our problems will be solved. Those of us who do suffer with the issue know we have done everything and that it's not hardware. Our horizons may be level for a brief time, but then the slant inevitably returns.

    If you stumble across a fix, please share. Good luck sir!
     
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  3. dkyacht

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    I'm going to do all the calibrations over again in my garage and not on my kitchen island. I've not done them since all the updates so I guess it's the simplest place to start.

    Good to know about the gimbal adjustment, although it seems more like a bandaid than a fix so I hesitate to "just" do that alone. I'll update in a few and let u know if there's any difference after the calibrations.

    Dave
     
  4. dkyacht

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    Ok so I'm not sure if I'm just a moron and missed it or its something that's different since the update but I think it's fixed. I started with the gimbal calibration, then the imu, and finished with doing the compass. As soon as I clicked the gimbal calibration you could see the live camera screen behind the menu snap level then finish the process. I'll fly it some more over the next few days and see if it sticks.....

    I should add that I did all this stuff before the update with no luck.

    Dave
     
  5. BudWalker

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    In the two directions showing a level horizon are the heights both the same?
     
  6. Oso

    Oso

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    For me it's the same. It looks good right after the calibrations so I'm encouraged. Sadly, even when it looks good on the table, simply opening and closing the settings menu causes mine to tilt a bit. Then during flight it goes full tilt again. The app would probably laugh in my general direction if it could.
     
  7. Oso

    Oso

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    I don't know what you mean by heights being the same in the two level directions. If you mean the gimbal angle, yes normally at zero degrees. If you mean altitude, yes at a fixed attitude the tilt changes as I rotate.
     
  8. BudWalker

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    Say, the tilt is observed in the east and west directions and it's level in the north and south directions. Is the height of the horizon in the north and south direction the same? If you do a 360 degree pan and there are no discontinuities in the horizon then the north and south in this example have to be at different heights.

    Are the directions that it's tilted always the same? Or is it random?
     
  9. Oso

    Oso

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    It will slowly change from tilted one way, to level, to tilted the other way, to level, etc. The same as many others have reported in a dozen or so threads. I don't know if it's always N/S or E/W when it happens to be level, though one user says that his issue was fixed when he did his IMU calibration with his camera facing North. When it's level, the height of the horizon appears the same if I am guessing correctly what you are asking.
     
  10. BudWalker

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    With this example suppose facing the east and west directions the horizon dips in the south direction, Facing east the horizon is higher on the left (north) and lower on the right(south), and vice versa facing west. Then, it mus be the case that the south direction has a lower horizon than the north.

    If the tilt always occurs when facing east or west then I have theory that explains where the tilt comes from. The problem with my theory is that I'm convinced it isn't valid. Never the less, I'd be interested to know if your observed tilt occurs facing east and west.
     
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  11. Oso

    Oso

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    If you're convinced that all of our horizon issues are not valid, then you and I will simply just need to agree to disagree. Cheers!
     
  12. dkyacht

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    Ohhhh ok I understand what your saying. I'm curious, what was your theory?

    Dave
     
  13. BudWalker

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    Sorry, I never said that your horizon issues aren't valid. In fact, I'm convinced they are valid. The only invalidity I see is in the theory I came up to explain the horizon issue.
     
  14. BudWalker

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    Ir's all based on the idea that tilt information is derived from the compass's geomagnetic inclination information. I'm pretty sure this isn't the case, it's derived from the accelerometers in the IMU Anyway, if the compass were calibrated tilted towards the north or south the value for the earth's geomagnetic inclination would be incorrect. Since the earth's geomagnetic vector is aligned north/south this error would show up as pitch error while facing north/south and roll error while facing east/west.

    To test this I built a test stand that allowed me to calibrate the compass with a steady tilt in the north/south plane with no tilt in the east/west plane. Looking at the compass x and z values afterward showed that compass's value for the geomagnetic inclination reflected the error introduced by the tilt during the compass calibration. Of course the accelerometers are independent of the compass and didn't show any error, i.e. down is the direction of gravity.

    I didn't actually fly it in this condition (call it fly-away angst). But, I did take the props off and start the motors. Holding a straight and level aluminum tube in front of the camera showed there was no tilt.

    As I said I don't think tilt info comes from the compass. Why would it? Much better tilt info comes from the accelerometers. That said, if your tilt only occurs only in the east/west directions then a theory including the compass is at least compelling. Does the tilt occur only when facing east or west?
     
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  15. dkyacht

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    Wow that's 1 hell of a theory.... Made my head spin a few times there. Overall I get what your saying. I guess more simply put it it's tilted while shooting east/west but not north/south your probably correct. Am I close??

    Dave
     
  16. BudWalker

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    I wouldn't say I'm probably correct. Makes more sense to use the accelerometers for tilt info and I wasn't able to cause the horizon tilt issue when I calibrated the compass with a tilt. But, if the tilt only occurs in the east/west direction then maybe somebody smarter than me can either build on or correct my theory to explain the tilt.
     
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  17. dkyacht

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    It does make sense I'll agree. I'm gonna try and fly alot tomorrow and see if it comes back. After 2 flights today I'm still good........

    Dave
     
  18. Oso

    Oso

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    Bud - if you have a chance, check out this post in one of the "tilt" threads:
    http://www.phantompilots.com/thread...f-the-tilted-horizon.47326/page-4#post-459641
     
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  19. Hjones62

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    @Oso Don't know if this might help or not but I had the slight picture being off as well. IMU calibration and Gimbal calibration partially fixed my problems. Come to find out 2 of my 4 plastic clear pins that secure the gimbal was missing...
     
  20. dkyacht

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