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Possessed? Or compass/satellite problem?

Discussion in 'Phantom 2 Discussion' started by gavinski, Feb 8, 2014.

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  1. gavinski

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    I have a brand new P2 which I took out for a maiden flight this morning on a nearby soccer field. I did everything I could to ensure a successful flight, with everything charged, checked for firmware upgrades. Even though the software indicated a compass calibration was not necessary, I went through the compass calibration process twice before the flight, seeing amber then green lights. I also made sure both S1 and S2 were in the up position. There were no big antennas or cell towers nearby.

    After waiting for all green lights, I practiced hovering for a short while, and then I started to practice maneuvers, going a little higher, altering pitch and yaw, and moving forwards and backwards. Then less than two minutes in, it just started to drift, and then accelerate away, even though I was not touching either stick. Rather than let it hit the trees or fly across the street I dropped the power and it landed hard, breaking a prop and popping out the battery. Most people recommend just turning off the controller to initiate RTH, but it happened so fast that my instincts just kicked in.

    The second flight, it did the same thing. It seemed to be responding well to the controls - hovering in place and turning as expected, before it just took off at top speed. This time the crash broke off two of the gimbal mount screws and another prop.

    After removing the camera and gimbal, I tried to do a much more controlled test. After going up just a couple of feet to see if it could hold position, it started to slowly rotate in a circle, then going in wider and wider circles and picking up momentum. I dropped it to the ground and called it quits.

    So, does this sound like a compass calibration issue? Or a loss of satellite issue? Or is it possessed by the quadcopter demons?

    I can post a video if that might help.

    Any help is much appreciated.

    UPDATE:

    Here is a link to the video: https://vimeo.com/86206273

    I have included a view from another gopro at the end of the clip.

    G
     
  2. FASTFJR

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    Video is always good!
     
  3. GundoLarry

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    I have no earthly idea what could've caused that. At about 2:40(??) it started to make erratic movements though.

    I wonder if the zenmuse gimbal is somehow causing glitches with the P2 board / circuitry!?
    Have you ever heard of anyone having this issue without a gimbal onboard?

    Perhaps there was damage done from the first crash...broken/cracked solder point.
    The way it just took off like that seems like it might be indicative of an intermittent type problem...solder joint making contact, but when the bird turns a certain way the contact is broken perhaps??
     
  4. gavinski

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    Thanks GundoLarry for the analysis. I don't think this behavior was the result of damage from a crash - because this was the very first flight. And after removing the camera and gimbal, it still wasn't stable, so that rules out interference from those devices.

    Afterwards I hooked it up to my laptop and did a full advanced recalibration, followed by a number of manual compass calibrations. While I was not optimistic, I decided to try and fly it again And you know what?

    It flew almost perfectly! I flew it for about 15 minutes, just practicing patterns and landings. I did notice it did seem to drift a little during a hover, maybe 2-3 feet and back again. I was studying the LEDs during the flight and I did notice they flashed amber briefly a couple of times, so I guess it did lose the signal a couple of times.

    So, if I had to guess, I would have to say there was something wrong with the compass/calibration the first few flights, which is surprising since I followed all the steps.

    Anyway, I had a blast once it was up and performing the way it should. I can't wait to go out again tomorrow.
     
  5. ianwood

    ianwood Taco Wrangler
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    First, it doesn't look like radio interference or lack of GPS. You lifted off and it held its position perfectly well. It was only when you started to get a little frisky with it that it started to act odd. I noticed just before it raced off that it looked like it was correcting its attitude rather violently. That could be user input (hard to tell but doesn't look like it), correcting for wind (doesn't look like there was any) or brief interruption in thrust (motor or ESC issue).

    If a motor, ESC or prop issue disrupts the thrust on one motor, that corner will dip, the Phantom will try to regain its attitude but in doing so it will run off in one direction until it crashes. Someone else here described it as a drunk man leaning too far in one direction and trying to regain their balance by walking quickly in that direction. The result is usually the same as what happens with the Phantom.

    But before we jump to conclusions:

    - Where did you do the compass calibration?
    - At what point (mm:ss) in the video did you feel the Phantom was no longer in your control?
    - Have you switched from Phantom mode to NazaM mode in the assistant software?
    - Did you get a series of rapid green flashes before taking off?
    - When did the LEDs flash amber?
     
  6. ianwood

    ianwood Taco Wrangler
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    I said disrupts as in diminishes its normal efficiency, not cuts out.
     
  7. ianwood

    ianwood Taco Wrangler
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    I really don't wish to get into a debate with you as to whether or not this is possible. Suffice to say, I've read several accounts that contradict your assertion. Your opinion is noted. Let's keep the thread on topic.
     
  8. ianwood

    ianwood Taco Wrangler
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    Good for you. You've made it PAINFULLY clear that you think it is impossible. I disagree based mostly on the fundamentals of physics. But, like I already said, your OPINION is noted. So, maybe you could be HELPFUL and offer an alternative perspective as to what you THINK might be the cause for this apparent flyaway. After all, we (including you) are all guessing, aren't we?
     
  9. ianwood

    ianwood Taco Wrangler
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    Of course you don't. Because that would be helpful. And being helpful is clearly NOT why you visit this forum. Either be constructive or go away.
     
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