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What causes ATTI mode?

Discussion in 'Pro/Adv Discussion' started by Rehaume85, Mar 13, 2018.

  1. Rehaume85

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    What causes ATTI mode to kick in? I got some awesome footage today, and I was going for my last shot, I went up 300ft and got my sunset shot then I was bringing it back down, as I was coming down it jumped into ATTI mode, mind you it was 11mph wind and it kicked into ATTI around a 100ft which immediately flung it into a tree and onto the concrete where my drone made its final landing : /
     
  2. ArgenBrewer

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    If I'm not very wrong, the on-board computer triggers the Atti mode when it finds discrepancies between the GPS data and the compass data. We could start by knowing how you handled the calibration, when, where, etc, etc.
     
  3. Oso

    Oso

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    If you post your flight we can check out the details and perhaps see why it went to ATTI.

    Just follow the directions here to find and upload the flight log file and then post the link for the flight back to this thread.
    Don't just upload the flight log file to this thread. You should upload it to the viewer and then post a link here.

    Of course only if you are comfortable doing so. ;)
     
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  4. Meta4

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    Atti mode is what you have when you fly without GPS.
    It can be because you are flying under cover and can't get sats, or because you switched to atti mode or because of a compass error that forces the flight controller to ignore GPS data.
    Your real question is: what caused the compass problem?
     
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  5. Rehaume85

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    I already bought a new one. that was a rough 24 hours
     
  6. solentlife

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    One aspect of ATTI that tends to be overlooked :

    ATTI mode does not automatically mean you have no GPS data ... what it means when it kicks in - is that if GPS related - there are insufficient number of Sats locked in for position PRECISION. ATTI mode can still have GPS providing RTH data though.

    ATTI mode basically kicks in when data from various sources - Compass / accelerometers / GPS gets out of synch / agreement or just plain GPS loses the required number of Sats. The AC Flight Controller then provides basic flight leveling without stable position hold / hover and YOU provide position hold / hover / directional input via the sticks.

    The matter that i find interesting is the number of reports of AC going into ATTI mode and crashing. This tends to indicate to me that AC may have been travelling at reasonable speed or descending fairly rapidly before it occurs. If the AC is in slow movement or hover - the transition would show by the AC drifting with the wind ...

    I have had ATTI mode kick in and also manually triggered by myself ... and never had any crazy antics of the AC ... even when moving at reasonable speed.

    Nigel
     
  7. ArgenBrewer

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    I could not understand the point, you mean that the cause of the fall may be that the AC is moving very fast at the time of the transition to atti, but on the other hand you affirm that you have put yours in atti moving fast without inconveniences. (It is likely that the translation is losing the meaning of your words ..
     
  8. Rehaume85

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    I wasn't descending and quicker than I normally do, and there were no obstacles or buildings in my path or vlos. it should have never entered ATTI mode. I believe that the system malfunctioned.
     
  9. Oso

    Oso

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    Have you decided if you'll post the log or not?
     
  10. Rehaume85

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    I decided not to, and I no longer have the wrecked p3p.
     
  11. randyvanscoy

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    I wish u would post it due to i have same problemsnwith m p3a. I have almost lost it twice . I was able to get it down with no crashes luckly . I posted my data here and did get some ideas, but maybe urs will show more light on whats causing the issues.
     
  12. sar104

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    Your statements "it should have never entered ATTI mode" and "the system malfunctioned" are not supported by anything that you have described. These aircraft switch to ATTI mode for very specific reasons, generally related to compass errors caused by taking off from magnetically distorted locations. Extremely rarely (in open flight) it is due to loss of GPS lock, and even less commonly it appears to be due to hardware failure, but neither of those is going to be the most likely explanation. However, without analyzing the flight logs you will never know for certain what happened.
     
  13. solentlife

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    I think your translation has missed the point.

    No problem.

    Nigel
     
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  14. Kmb

    Kmb

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    I have found compass errors cause the atti mode switch with my PS3. Practice flying in atti mode. You will need that skill.
     
  15. Andy9

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    I think that the only thing about flying in ATTI is to be aware of it instantly as the AC will immediately drift with the wind. In stronger wind it goes pretty fast.
    But if you miss that point on the screen you'll be very likely 'Blown with the wind', if you like filmography.
    If the drone is nearby it's pretty easy to fly in ATTI. You can see it and correct the curse accordingly. If not it is very tricky to fly only by the FPW on the screen and without clear orientation point you very likely get lost.
    I'm not quite sure if you still have a telemetry in ATTI mode as you have not GPS data so the AC can't locate its position.
     
    #15 Andy9, Mar 19, 2018
    Last edited: Mar 19, 2018
  16. sar104

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    It's not just the drift that catches people out - it's that unlike in GPS mode, when you center the sticks, it just coasts rather than stopping. You have to apply reverse stick to stop it.
     
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  17. cneedelman

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    Yeah the drift caught me on my P2, only a few hundred feet out and headed towards some trees, had to think fast didn’t even realize I was in ATTI, brought her down as fast as I could, pretty much a crash landing. I’ve since replaced the patch antenna and have no GPS issues, also bought a P4P.
     
  18. Andy9

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    Yes! This is precisely what we are talking about. Each pilot must try to notice that the AC turns into ATTI as soon as it possible.
    And of course must be aware of direction the AC is heading to. Otherwise you may even worsen the situation.
    And that's why it is always recommended to fly towards the wind, so even in ATTI you need to do almost nothing because the AC is coming to you. You just need to correct the curse and land it or continue to fly in ATTI. Most likely the AC will sooner or later turns back in GPS mode by itself.
     
  19. kevinp3s

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    If the AC goes into ATTI mode and you hit RTH via the S2 will it work ?
     
  20. sar104

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    No. The aircraft does no active positioning in ATTI, and thus cannot navigate to a location.
     
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