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I thought I lost another Phantom

Discussion in 'Pro/Adv Discussion' started by Askaraboz, Jul 7, 2015.

  1. Askaraboz

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    Took my second phantom 3 out tonight at the art museum in Philly. It's my 56 flight. Took off as usual and I started taking it straight up right away. Then all of a sudden it decided to go left and away from me straight for the museums wall. I almost **** my pants and kept the left joystick up in hope to clear the building and I swear I made it by no more than a foot. Then it loses signal, and not just loses signal I get no info on the phnatom at all, like it's turned off. So I think it must have crashed into the roof a little further up cause it's a huge building. Just for the **** of it I started walking around the building in the hopes that maybe it was just hovering somewhere. And then I got the signal back and the craft was more than half a mile away. So I hit return home. When it got closer I saw it going back but in circles. WTF?! So I stop return home and want to guide it back myself. It works fine for bit but then it starts spinning in a small circle. Then I hit return home and it starts moving normally like it should. Then again I take over and bring it down and land it. I have no idea what is happening with it.
    You know whenever I was reading posts of crazy things happening to phantoms I thought to myself it's just dumb pilots error. But now that it happened to me I'm starting to get worried about how well these things are made.
    Anyone has any idea what the hell could cause such behavior?
     
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  2. snerd

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    No idea, but my first guess would be that there is a ton of electrical/magnetic interference in an urban setting like that. Did you calibrate the compass before liftoff? Home point registered?
     
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  3. FRM

    FRM

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    Did you have a good GPS signal? Sounds like the return to home was confused Internally. Was it coming back or just spinning in the sky? In the city it might be some fluk interference ?



     
  4. Askaraboz

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    Yes, everything was calibrated, and it was going home meaning it was moving to the return point while making circles, it made a total of three circles each getting smaller from what I see on the flight record. And I flew it in the location multiple times without any problems. I mean I only fly it in the city an never had issues like that.
    When it started spinning the second time it was doing so in one place since it wasn't returning home.
    I'm leaning towards issues with the control sticks. But then again I wasn't even touching the right stick when it started movingn sideways.
    Oh and yes GPS was perfect too.
     
  5. snerd

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    Hopefully someone else will be along to offer more help than I can. Keep us posted.
     
  6. BenDronePilot

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    Actually in that environment if he did calibrate the compass there, that could have caused the problem. Compass calibrations should only be done in a clear relatively radio and electrical interference free area.

    Without flight logs or some form of diagnostic data there is really no way to say for sure what happened. It could be calibration issues or it could very well have been some form of RF interference.

    My original Phantom 2 on one of its earlier firmwares just prior to the no fly zones being added. I had a strange behavior on at least 3 occasions when flying in my neighborhood not too far above house / tree levels. It began agreesively flying in circles without my input. I did cycle on and off Atti and was able to influence the movement while it did that until it stopped. In the end I chalk it up to interference. Also later firmwares made improvements to the GPS and compass as well as GPS declination issues. Though I've yet to fly my P2 in my area with the newer firmware.
     
    #6 BenDronePilot, Jul 7, 2015
    Last edited: Jul 7, 2015
  7. caffeinated

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    Ironically one way to confirm stick issues would be to turn the controller off. If return to home worked then it was faulty controller signals. Issue with that is if it was NOT that then you wouldn't be able to manually correct so I personally wouldn't have the intestinal fortitude :)

    These are the types of threads that concern me. VPS issues I can solve temporarily. Incorrect gimbal warnings I can solve or ignore. These ones, which there have been a couple of now, of the craft taking off in a certain direction are far more alarming and I haven't seen anyone with a definitive answer to it yet.
     
  8. kdrak

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    Perform an IMU calibration
     
  9. 30secs

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    Post a picture of the flight!
     
  10. Cyril

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    Hi,

    I'm flying my P3P from an offshore rig (a lot of electromagnetic interference) and I sometime have this kind of behaviour (circling, spinning, with no stick input). First time I almost crashed but now when it happens I switch straight to ATTI and land it manually.

    Yesterday, 3 flights with 3 batteries. Compass calibration done before the first flight, Compass Mod > 1500 and steady (hand launching) before each flights, the first two flights without any problem, the third flight I had the same problem again (huge drift and spin straight after taking off).

    I think it's definitely a compass problem. In my case, I'm sure it is :)
     
    S5S5G6 likes this.
  11. cdronefly

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    That has to be an area with an incredible amount of EVERY kind of EMI. From the vast arrays of high tension wires along the train tracks (across the river) to the proximity to downtown, etc.

    In areas like that you fly 100% at your own risk. One of the first P3's lost was in a similar high RF area in Boston.

    The P3 is a decent machine but expecting it to be military spec is a little too much.

    It may work - or you may lose it. That's the risk in such situations. If you lose it, consider that you got 60 flights at $20 each. If you keep it -maybe you got some nice pics.
     
  12. Volantis

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    Despite the picture of calm, stable environments for GPS signals that many like to imagine, the radio environment is far from calm. Rapid changes in ionospheric electron count, and ripples in the Earth's electric field caused by cosmic rays, ground currents, and man made electrical events can randomly wreak havoc on the stability of GPS signals. Even NASA and the militaries have to contend with these fluctuations.

    Instead of complaining about the P3P, we should fly with a safety margin and not get too tempted to push the technology to its limits (flying close to buildings and trees, near high voltage lines, out of line of sight, etc). We need to accept the fact that we can be the victim of anomalous guidance signals.

    When I take off, I don't go shooting straight up like a bat out of hell, I lift to about 20 feet, check my video settings and observe the flying characteristics, and then I head out on a preplanned flight path. I always fly with a second person who can keep their eyes on the craft to observe unusual situations.

    Flying a real drone is nothing like the rock solid control that occurs in video games. The radio environment is susceptible to occasional turbulence. I have a microwave sensor that continually monitors the background microwave activity here in the middle of farm country. Particularly around the evenings before sunset, there can be sudden bursts of background microwave activity related to weather patterns. I also monitor ground electrical currents and ambient magnetic flux density, which also show occasional spikes of activity, which also are related to weather but also to solar activity and processes within the Earth.

    Imagine the local radio environment to look similar to the weather environment, or an ocean environment, or the interplanetary space environment. There is occasional turbulence that can mess with the GPS signals, which is why the GPS network cannot rely only on relativistic corrections, but must be constantly recalibrated through empirical measurements.
     
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  13. ianwood

    ianwood Taco Wrangler
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    Most likely your compass was not working properly. There are three possibilities for this:
    • Bad compass calibration.
    • Presence of strong magnetic influence in take off area.
    • Presence of strong magnetic influence in flight area.
    Not necessarily. I fly in urban environments extensively. I have logged magnetic and RF data for numerous flights. You can fly almost anywhere using simple precautions. There are very areas where RF and/or magnetic interference will cause this kind of incident.

    Unlikely. What you're describing is GPS drift. It's a much bigger problem for absolute positioning. Normal Phantom flight only uses relative positioning. DGPS will further negate this impact as do the short duration flights given that drift happens slowly.
     
  14. cdronefly

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    Have you flown in central boston, nyc, philly, etc. or just spread-out and low rise places like LA?

    Are you familiar with places such as the Art Museum, Charles River (boston), etc. in terms RF? I'd be interested in seeing your RF measurements for such areas.

    These particular areas are probably in the top 1% of areas as far as radio waves of all types - combine millions in population with universities doing RF stuff as well as thousands of housing units (mid and high rise) with RF. To that add vast underground infrastructures containing metals, wires, etc.

    I think a good pilot could fly in the Art Museum area, but they would have to be very careful and maybe NOT calibrate the compass there.

    It's all a matter of risk. If the pilot is willing to take it - and assuming the place is legal and legit to fly, that's a valid decision.

    FYI, I lived quite near there for a few years. When I walked outside 24/7 I heard the loud hums of the power plants nearby. The 30th street station rail yard nearby contains amazing amounts of power lines for the trains - let alone serving as a conduit for most every type of utility line (under and above ground). That same river is used a a conduit to broadcast most TV and Radio to the entire city, although I doubt that is the problem. But it's definitely a thick soup around there.
     
  15. ianwood

    ianwood Taco Wrangler
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    Some examples:

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    The last one being LA where I have seen some of the fastest RSSI drop-offs and magnetic fluctuations of >400┬ÁT but nonetheless without loss of control.

    I've flown under 300,000kV power lines, in giant industrial areas, and in the most densely packed parts of several cities. I've seen some weird stuff but never a full loss of control. Almost always, the type of loss of control described by the OP is either bad compass calibration or magnetized take off point.

    And NEVER calibrate a compass in an urban environment.
     
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  16. ranges

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    When I get into a high EMI area my Phantom starts to ferroresanate.
     
  17. CYeutter

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    Recently I attempted to film city hall in my city because it's an large and interesting building. Pre-takoff everything looked perfect. At a height of about 20 feet, I got a "compass calibration error due to strong electromagnetic fields". ( not sure of the exact verbage ). The P3 started moving around on its own. I was able to land it however. I tried a slightly different location and got the same result. Later, in the park, it flew perfectly. I guess I'll skip filming city hall.
     
  18. Askaraboz

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    I've tried to export flight records to be able to show them via flightreplay.com but the last three flights I can play on my phone but they are not among the files in the FlightRecord folder on my phone. There is no green circle to the left of them as is with the rest of the records. That is weird. I guess I could just post screenshots but that's lame.

    I was filming fireworks in the same area just 2 days prior without any problems, there were 3 other phantoms there as well.
     
    #18 Askaraboz, Jul 7, 2015
    Last edited: Jul 7, 2015
  19. Askaraboz

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    After I launch it if everything looks ok I go straight up because I'm in the city and want to go up and away from buildings and power lines and people that are always around, and if I have it hover for any period of time they come over and start talking to me and I'd rather keep an eye on the bird. And sometimes I just don't feel like explaining what it is and how much does it cost etc. etc. I guess it has to do with flying in the city. And I don't have a spotter so I always fly by myself. Half the time I do it in the middle of the night, not too many people would be willing to accompany me at 2 a.m. Also I travel on a motorcycle so can't really take anyone with the backpack taking up all the space. My girlfriend would be useless as a spotter.
    However I think you're right about predetermined flight routes. The more I fly the more I start to plan ahead as to where and how I want to fly it and check the route for possible obstacles. It's more efficient and safe that way.
     
  20. richardseguro

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    Flying in circles...over houses...could it be interference with home wifi's...microwave ovens... from a wireless speaker...remote control TV...

    Could this be possible?
     
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