Welcome to PhantomPilots.com

Sign up for a weekly email of the latest drone news & information

Altitude issues in waypoint mode

Discussion in 'Pro/Adv Discussion' started by Motolorax, Nov 27, 2015.

  1. Motolorax

    Joined:
    Nov 16, 2015
    Messages:
    9
    Likes Received:
    0
    On my first waypoints mission my phantom flew below the altitude of the home point and did not seem to even approach the altitude that the waypoint was set at.

    My first question is: how do these phantoms calculate their altitude? I know they have barometers but do they not also work in relevance to the homepoint?

    I'm using the latest firmware and flying the P3P with an ipad mini 2 with cell. I have read here DJI Forum|Waypoint Mission loses altitude on 2nd pass. about altitude variance and I would post this on the DJI forum except I can't because I never recieve the confirmation email.

    So, I took off from ground level (obviously) and then flew out in front of the house to set the fist waypoint at 11m alt, and then threw in 2 more waypoints and engaged waypoints. The phantom returned to the first waypoint but plummeted to below ground level from where I was standing (the ground slopes away in front of the house) and was well below actual 11m from the grass when I flicked it back to P mode and safely returned to home. If it was using the home-point as a reference for altitude I can't see how it did this through recalculation. I will be trying again as soon as my nerves have settled and will work at a much higher altitude at first (although for the sort of cinematography i do I need to be flying at relatively low alt.

    Is anybody else seeing these sorts of errors and understands their cause??

    Many thanks.
     
  2. PVFlyer

    Joined:
    Jan 27, 2014
    Messages:
    1,484
    Likes Received:
    125
    Location:
    Hong Kong
    Did you turn on VPS or use barometer only for altitude?

    We have an Important Notes section for Mission Planner users as below.

    • Aircraft height (altimeter) may easily vary 20m (66ft) off the actual height after aircraft flying and heating up several minutes. You are recommended to set waypoint height minimum 25m (82ft). For example, if you set a waypoint height 25m, when aircraft reaches such waypoint 10 minutes later, the actual height might be only 5m (17ft) depending on the discrepancy of altimeter, though the altimeter is still reporting 25m height. This is likely a generic issue of DJI products family regardless apps or even without using app.
     
    Jeffdj likes this.
  3. Motolorax

    Joined:
    Nov 16, 2015
    Messages:
    9
    Likes Received:
    0
    Thanks for the reply. I did not knowingly turn on the VPS, I will check the log, if it contains that info. The explanation makes sense and the weather here in southern New Zealand is very dynamic at the moment which won't help I'm sure. I'll fly again if the wind drops and work out if i was using VPS or not,.
     
  4. Adammmmm

    Joined:
    Nov 12, 2015
    Messages:
    5
    Likes Received:
    0
  5. Motolorax

    Joined:
    Nov 16, 2015
    Messages:
    9
    Likes Received:
    0
    As it was my first waypoints experience I'm aware I might well have done something wrong in setting up the mission, but the hight variance was dramatic! I've not used Litchi and given my limited experience I'll probably stick with DJIGO for now but from what I'm reading it seems the same generic barometer variance issue would still apply.
     
  6. Spikeymous

    Joined:
    Oct 10, 2015
    Messages:
    30
    Likes Received:
    21
    If setting and getting the altitude to work correctly, then using this app, or any for waypoints is basically setting you up for crash. I don't understand how this or any waypoint app can work properly. I guess you set the altitude for 100m or more then if it drops you won't hopefully hit something. This is an issue that definitely needs to be addressed by all before we can safely use this copter for waypoints. I have 2 qrx 350 pros I can fly using the PC mission planner and never have had any altitude issues. Not to bash anything, but now I'm wondering what's so great about this bird?
     
  7. Motolorax

    Joined:
    Nov 16, 2015
    Messages:
    9
    Likes Received:
    0
    Price and convenience for me. I started out with an s800 with zenmuse and a GH3, back in the day when GPS couldn't be relied upon in the deep south so we only flew attitude. I needed to take a pilot with me on the shoots (which was great fun but obliterated profits) and if we crashed I lost most of the project margin. Against that experience, a nearly disposable phantom seems like a great idea.

    I do wonder if there is a way that VPS could be allowed to override altitude if anything is detected <10m drop phantom. It wouldn't solve the course variance but it might reduce the probability of a crash if you can't keep your eyes on the drone because you're focusing on the shot. Or get an inspire...
     
  8. Spikeymous

    Joined:
    Oct 10, 2015
    Messages:
    30
    Likes Received:
    21
    I do like the phantom 3a so far, no real issues for me yet, but limited experience with this. I have flown my other quads for a couple years and never had all the issues in that forum either. I still believe as you probably know most issues are pilot errors.
     
  9. Motolorax

    Joined:
    Nov 16, 2015
    Messages:
    9
    Likes Received:
    0
    OK, since this event I've taken more careful note of altitude changes and in P-GPS and atti-mode I've observed lots of both gradual and abrupt altitude changes. I've never noticed them before because I don't fly assuming the phantom knows precisely where it should be (although to be fair it does a **** good job of exactly that for a cheap piece of consumer electronics). Waypoints works fine, just get somebody to keep an eye on the drone if you're focusing on the images as I usually am.