There has been a lot of discussion recently on DIYDrones about GPS accuracy, the reliability of autonomous flight modes like Return to Home, and safe flying conditions. These are all valuable discussions to be had, but it is also is helpful to consider how well GPS-based positioning works in the best of conditions.
To generate the plot above, I launched and RTLed Solo 26 times and recorded the landing position with tape. These flights were conducted on a flat rooftop in Berkeley with a totally unobstructed view of the Southern sky. I typically had 8-12 satellites for each one of these flights.
I then took an image from the air using Solo with a flat-lensed GoPro and measured the angle and distance from the takeoff zone in ImageJ.
Over these 26 landings, the maximum deviation was over 6 feet and the mean was around 3 feet. I hope this is helpful for those new pilots in the community who are just beginning to experiment.
If more precise landing are desired, there are some excellent dev options out there like IR-Lock, which does not rely on GPS, and Piksie, which does.
Comments
Mock-up testing inspired by SpaceX :)
@Steve The average landing position is at -2 feet in X and 0 feet in Y.
The actual takeoff point recorded was probably about the average of all those landing points.
Nice test! It would be interesting to understand why the left part is the landing area most populated by the marker, if the square is the takeoff point.
Nice!
We hope to get some waterproof Beacons installed on the dock. We need better footage of our questionable watersports. :) The idea is to launch from the dock, run FollowMe (perhaps behind the 60mph JetSki), then RTL back to the approximate GPS coordinate of the Beacon for an automated 'Precision Landing'.
Water is actually one our most challenging operating environments wrt target detection, due to the intense, random sunlight reflections. But we think we have it figured out now.
Excellent test.
From this you might draw the conclusion that a 16+ foot diameter clear landing area could be sufficient.
That actually seems pretty reasonable, although I am sure, strong wind or gusts (or the characteristics of the particular copter) could change the results quite a bit.
It would be interesting to see some others repeat this test with various copters under various conditions to see what more generalized expectations might result.
Great baseline!
Best Regards,
Gary
Nice to see the real-world test results.