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Ground ground station question

Discussion in 'General Discussion' started by philipfretwell, Feb 12, 2014.

  1. philipfretwell

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    When the Phantom is on a mission and told to go from point A to point B at 100', does it maintain its relative height above ground of 100' when it goes over a hill..

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  2. Pull_Up

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    Re: Ground ground station question

    No radar altimeter in the Phantoms yet, I'm afraid! Height information is actually altitude (i.e. barometric) only, and bases the "zero" level on the reading at the take-off point (this is for all flying, not just ground station - applies to RTH, for example). It won't see the hill, or the house, or the electricity lines or whatever else is in the way and over 100'. :)
     
  3. philipfretwell

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    Thought it may use the height info which is part of the info in the gps stream...

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  4. Pull_Up

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    Re: Ground ground station question

    GPS-derived height data isn't sensitive enough to allow it to hover at the factory spec +/- 2.5ft. Even if it did use the GPS data it still wouldn't know the terrain height as there's no internal or external topographical data used. Nothing to stop that being programmed I would have thought (except time and money), it's just a heck of a lot of data to crunch, not to mention licensing the source of the height data and making sure it's accurate, etc - probably from existing aviation data providers. Even then it would only know terrain details from a database - it wouldn't have man-made structures on it unless they were so tall that general aviation traffic needs to be aware of it (large chimneys, TV towers, etc).

    I'm sure it's only a matter of time, though, before someone brings out an affordable (and light) means of quads being able to detect their distance and/or height from other object/terrain. After all you get "radar" cruise control in cars now, which does the same thing albeit horizontally...
     
  5. ElGuano

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    Re: Ground ground station question

    NAZA is a black box. We KNOW the barometer is used for real-time altitude adjustment. I think it makes sense that GPS altitude information is somehow taken into account as well, but there's not a lot of data out there either way. Between the GPS, compass, gyros/accelerometers, and barometer, there are a lot of complementary systems for determining relative and absolute position, how the NAZA mixes all that is part of the secret sauce.

    In either case, altitude is entirely based off recorded reading at takeoff point. If you take off on a cliff and drop down 300ft, it will go up 360ft if told to ascend to 60ft height (as in RTH). It is entirely blind to hills, trees, buildings, altitudes it has previously traveled, etc.