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How is altitude treated during follow me mode?

Discussion in 'Pro/Adv Discussion' started by Evel_Knievel, Sep 24, 2015.

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  1. Evel_Knievel

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    How is altitude treated during follow me mode?

    In other words if you tell the bird to follow me while you're at the base of a mountain, then start up the mountain, is it going to run into the side of the mountain? Or is it smart enough to keep the same altitude above the mobile device?

    Can't find any good instructions or manual on this...and it's super flat where I am or I'd test it.

    Thanks!
     
  2. Othan1

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    Good question. My quad is in the shop for repair or I'd test it out for you but would love to hear some actual users' experiences.
     
  3. bobmyers

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    On my list to try-- great question!
     
  4. Mako79

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  5. Evel_Knievel

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    Thanks! Answers that!
     
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  6. Signals

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    I am pretty sure that is why the Autopilot App prefers devices that are equipped with a barometer like the Air 2. The user is required to calibrate the barometer using the software before using some of these functions. See their page Autopilot - Autoflight Logic. The DJI app does not use this but would imagine that that will be added for the GO app soon as well.
     
    #6 Signals, Sep 25, 2015
    Last edited: Sep 25, 2015
  7. Erroll

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    I tested both GO and Autopilot this week, although I went from high to low.

    The DJI GO app doesn't compensate for altitude and by the time I reached the bottom, my car was hardly visible on the screen. Going the other way would cause a certain *splat*!

    The Autopilot app gives you choices - power, (no compensation), use Barometer (if the device has one), or use GPS, if the device has it. I tried power and it behaved like to GO app. I don't have a barometer so I used the GPS option next and it worked like a charm. The quad stayed the same distance above my car all the way down the hill.

    Autopilot does recommend upgrading to a device with a barometer because of the superior accuracy, but I was quite pleased with the GPS's accuracy.
     
    #7 Erroll, Sep 25, 2015
    Last edited: Sep 25, 2015
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  8. Signals

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    GPS is not suppose to be that accurate for the z component but then if you have a GPS on the ground (in your device) that you use to correct then It makes sense that this would work as well since they would both be seeing (close to) the same satellite constellation. That is how the barometer readings being shared would help as well.

    Thanks for sharing your tests.
     
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  9. Erroll

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    Here is a recent flight using Autopilot's 'Follow' mode. The drop in altitude from the tar road down to the river is around 100 meters. I selected altitude by GPS, and you can see in the video that the quad followed my altitude quite accurately.

     
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  10. Signals

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    Nice. That is good to know and now that I have a device with GPS I can try it depending on weather.
     
  11. StratocasterDave

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    Hope I'm not hijacking the thread but why does the video sway left to right like that? I haven't done much of FM, is there a way for it to follow smoothly?
     
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  12. Erroll

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    No hijack - that is a good question!. I have also remarked on it elsewhere on this forum, but I have not had any explanation. I was travelling quite slowly so it does not appear to be speed related. The biggest 'sways' are when one turns, almost as if the quad has to 'catch up'.
     
  13. MoOriginal

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    Would that's not be down to the autopilot algorithm used for steady or turning flight?
     
  14. Damieon VZ

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    from that, it looks like the UAV won't be adjusting it's own altitude. Sorry for your crash, but thank you for the insight!
     
  15. mirrorimage

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    Where is this beautiful place?
     
  16. Erroll

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  17. okestone

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    My P3S follows at a certain altitude, (as opposed to a certain distance above ground). I almost crashed it before it dawned on me what was going on.
     
  18. Erroll

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    If the P3S behaves like the P3P then that is exactly what will happen. The DJI GO app maintains the altitude (relative to the launch point) at which the follow-me mission was started. . As has been said several times, the Autopilot app can be told to use the device's GPS and/or barometer to determine following altitude.
     
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  19. nhoover

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    The Go app does not follow vertically that is, whatever height you set, it stays there absolutely. Litchi on the other hand (if you set it) will follow relatively which is what you want. It works if your mobile device has a barometer. Works great with my Nexus 9.
     
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  20. Erroll

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    I'm looking forward to trying Litchi on IOS. I have upgraded to an iPad Air 2 so now I have a barometer too. Watch this space....
     
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