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How Accurate Should RTH be?

Discussion in 'Inspire 1 Discussion' started by Scotflieger, May 18, 2015.

  1. Scotflieger

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    I have noticed that the accuracy of the I1 Return to Home (RTH) point was doubtful as I always had to make manual corrections to return to the take off point. So today I went to the local playing field and conducted a series of tests using Static (take off) and Dynamic (controller) Home Points with Smart, Low Battery and Fail Safe RTH modes.

    My findings were that within 20m of the Home Point, the I1 will simply lower the landing gear and land vertically. Over 20m the I1 climbed to the set height (20m in this case), pointed to home point, lowered the landing, flew to towards the home point, returned to the hover and descended. However, on all tests the I1 only returned to 15m of the Home Point on the radial from the Home Point to the last position. This distance was displayed on the Pilot App Distance and measured on the ground. This was the same for both Static and Dynamic Home Points - and the latter does work when the controller has an accurate GPS position. I did try walking away from the desired landing point on the opposite radial for 15m and then setting the Dynamic Home Point. The I1 then returned to the correct landing point to within 2-3m laterally.

    As a confidence test, that I recommended everyone to try, I switched the controller off on several occasions. The Failsafe RTH activated after 3s and the I1 return to home but only to within 15m of the set point.

    Have other pilots experienced this error or am I alone?

    I am using FW 1.2.1.3 and iOS Pilot App 1.1.1. Wind speed for test 0.8m/s (2mph).
     
  2. Loaderbull

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    15 meters seems a bit off? I've had it back to me (manual RTH) within 2 meters...
     
  3. Scotflieger

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    That is more like I would expect. 2m is safe, 15m puts it in a tree.
     
  4. Kilrah

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    I haven't tested RTH with the latest FW, but on my tests with older ones it was within 5m most of the time.

    But it's something that obviously varies, possibly quite significantly and at any time based on GPS signal quality, I wouldn't expect 15m to be "wrong".
    If 2m is safe but 15m is in a tree, don't take off there ;)
     
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  5. Scotflieger

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    I would agree about GPS accuracy but it does appear to be correct. The Pilot App is displaying 14-15m distance away from the home point after landing.
     
  6. Kilrah

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    Yes it "appears" to be correct but it doesn't actually tell you the precision of that reading, the aircraft however has that info.
    It may know "I'm at 15m but that reading currently has +/-10m precision, so I'm better off just landing here instead of trying to get back to 0 as that might be even more wrong".
     
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  7. theheliguy

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    I only tested mine twice and both times it was between 12 & 15 meters. I will test that again once it gets back.
     
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  8. Scotflieger

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    Update: I have emailed DJI with video and Pilot App screen grabs showing the consistent 14-15m error on RTH I have been experiencing. They acknowledge that there is an issue and are investigating.
     
  9. huppe

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    Tested about 10 times and the range goes between 15 mtr and 1 mtr.The 1 mtr was without wind so it was pretty good.But i guess that the RTH function is more to get the Inspire back close to "hearing range".Once i have visual contact I switch to manual and land the Inspire by myself.But it was only testing since I never used RTH with normal flying.If you get confused where the bird is just realease the sticks and have a deep breath and a look at your radar.and try to get it back.
     
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  10. Carlsberg

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    Same here, I always take control of the bird once I regain it.
    I have never tried auto take off or auto land, no flippin way! (why?)