Phantom Fly-Aways - Debunking & possible solutions

Re: Phantom Fly-Aways debunked & possible solutions

This is a good theory, but unfortunately it is not correct.

I'll explain why:

When you are using google maps and you have a blue dot many miles from where you are actually located, this is due to gps not enabled or gps not connected to enough satellites to get an accurate location reading. So what google maps does instead is it uses wifi and cell tower triangulation to estimate where you are located. This allows the user to start using the map software right away.

However, after a few seconds (minutes) the phone will be able to located enough satellites that the cell tower and wifi triangulation is no longer needed, and this results in the blue dot magically jumping to its right location (within 3-5 meters).


With our phantoms, we don't have any type of triangulation other than gps triangulation. This is why we must wait until there is a minimum of 6 satellites before the green lights begin to flash. This results in the 3-5 meter accuracy of your location (usually even more accurate than that due to 6 satellites being required for gps lock).


Therefore, the phantom doesn't have the issue of estimated location because it always has enough satellites to know exactly where it is.
 
Re: Phantom Fly-Aways debunked & possible solutions

Jayson Hanes said:
that is a result of the range limiter.. I had upped the max altitude to 2000 feet

Excuse me ... I meant radius... there's two different limits that can be set... I've never seen the pop up for radius warning so I'm just curious if it's there and if it works in the scenario I described in the OP
 
Re: Phantom Fly-Aways debunked & possible solutions

amkorp said:
Therefore, the phantom doesn't have the issue of estimated location because it always has enough satellites to know exactly where it is.

That is a good rundown of how things are supposed to work... The cell phone example I had referred to was a common note I figured every one could relate to but for your explanation it was a bad example.

Inaccuracies in GPS positioning exist in many other devices and can be attributed to many factors including not enough satellites to triangulate... The problem is when the GPS unit triangulated improperly on start up and interpreted that data as correct... then as the process continued to acquire more satellites the initial data hasn't refreshed because the target hasn't moved and attempted to triangulate position again...

I still have a buddy that works at ComSat in Hawaii and his response when told him these drones fly by GPS was "you guys throw $1300 up in the air relying on THIS to keep it there?!?... Good luck with all that bro"... He knows way more than me and also explained how I should check the solar weather warnings on the days that I fly for similar reasons.

Anyway... you are correct in your description of how it's all supposed to work... I'm just trying to avoid situations as described by others when it doesn't work perfectly one out of thousands of flights.
 
Re: Phantom Fly-Aways debunked & possible solutions

I have been using Naza mode for awhile now and This whole theory makes a lot of sense there have been many times where I flicked the S1 just to see if the return home worked and it just started flying off in a random direction. I always check before I fly out of view to make sure return home is working. But I would say 1/3 time i have to intercept the process and fly it myself.
The return home feature on my Blade 350QX always works so I'm glad this was brought up.
 
Re: Phantom Fly-Aways debunked & possible solutions

Interesting theory. Although it cannot explain the large number of flyways that occurred prior to DJI implementing the ability to set limits last year.

But most flyways occur after the user has taken off and has been successfully flying for a given amount of time.
if one somehow manages to take off (after acquiring GPS in the first place), wouldn't it then try to fly back within limits immediately?
 
Can someone tell me EXACTLY where the red icon on the "Find My Phantom 2 Vision" screen is getting its location from? Is it the last known GPS position? i.e. if I am sitting at my desk at work and I look at the screen and the location of the red icon, where did that position come from? Cause for me it is right where I powered it off this morning. If it is the last reported GPS position and it is in the right location when I am sitting there waiting to take off, and I save that as my home position using S2 flips, then if it does a fly-away........well I guess I shouldnt threaten anyones life on here ( <whispers DJI> ).
 
boy-that-escalated-quickly-anchorman.gif
 
I am still learning all this stuff but why would you not switch to manual mode as your rig is flying away to no where. I get that some fly aways could be caused by the controller losing connection, which manual mode would not fix, but I have seen and heard people still having some control, or perceived control. I think your idea is possible. I have seen GPS do weird things.
 
Many people are not capable of flying manual mode. You get a false sense of security even in atti, the NAZA is doing the heavy lifting. Here is a little taste of manual mode:

If you are impatient jump to around 3:30 and watch the last minute. http://www.youtube.com/watch?v=Hq1yQEZmZmQ still makes me laugh, that guy has a good sense of humor!

http://www.youtube.com/watch?v=RwcTVFsaWvI

Because it is so dangerous if you haven't learned to fly manual before switching into manual (which does provide somewhat of a chicken and egg problem) most people leave the switches as gps/atti/rth rather than gps/atti/manual so would not have access to manual even if wanted. I am tempted to play with it, the big thing that is so different is you must do the opposite stick action for every move and the gains are not restricted (or if they are, they are wayyyyy higher by default).

On the plus side you can do flips and rolls :)
 
DJI - The Flyaway Trailer!

I want to talk to someone in charge at DJI...

You are not fooling anyone when you say what happened to my Phantom was a natural disaster..

You're lying...

It wasn't Pilot Error... It wasn't a GPS glitch...

Because what's really happening is that DJI is hiding something out there...

AND IT IS GOING TO SEND US BACK TO THE STONEAGE...

You have no idea what's happening to our Phantoms....

WE HAVE A RIGHT TO KNOW!!!



13897748247_83a7529246_z.jpg


God help us Phantom Flyers!


PS: Very interesting theory... I think you're on to something...
 
Hmmm...

It is my understanding that our cell phones use what is called "Assisted GPS"... Meaning multiple methods are used to determine your location... One being GPS the other being Cell Tower Trianglation...

I've seen my phone/ipad do that crazy location adjustment, however, I've never seen my Car's Navigation or my Garmin GPS device do that... Once those devices have a set GPS lock, you end up being where it says...

Our phones use trianglation first while waiting for a decent GPS location... Since the Phantom uses an actual GPS receiver, it's GPS lock would be really close with a minimal of 6 Sats... That's probably why DJI wants us to wait for the sat lock before taking off...

Just my opinion...
 
PJA said:
DJI - The Flyaway Trailer!

I want to talk to someone in charge at DJI...

You are not fooling anyone when you say what happened to my Phantom was a natural disaster..

You're lying...

It wasn't Pilot Error... It wasn't a GPS glitch...

Because what's really happening is that DJI is hiding something out there...

AND IT IS GOING TO SEND US BACK TO THE STONEAGE...

You have no idea what's happening to our Phantoms....

WE HAVE A RIGHT TO KNOW!!!



13897748247_83a7529246_z.jpg


God help us Phantom Flyers!


PS: Very interesting theory... I think you're on to something...

That was epic... I just spit my coffee...

PS: you owe me a new keyboard
 
semaj said:
Hmmm...

It is my understanding that our cell phones use what is called "Assisted GPS"... Meaning multiple methods are used to determine your location... One being GPS the other being Cell Tower Trianglation...

I've seen my phone/ipad do that crazy location adjustment, however, I've never seen my Car's Navigation or my Garmin GPS device do that... Once those devices have a set GPS lock, you end up being where it says...

Our phones use trianglation first while waiting for a decent GPS location... Since the Phantom uses an actual GPS receiver, it's GPS lock would be really close with a minimal of 6 Sats... That's probably why DJI wants us to wait for the sat lock before taking off...

Just my opinion...


True stuff right there bro... In a perfect world, this is how it's supposed to be... but even at Garmin customer support center there are thousands of calls per day trying to resolve issues...

Take a look at lines copied directly from a training manual to deal with customers having issues and how these issues may be explained to give time for GPS data to correct itself...

These are scenarios that can cause your GPS device to be off by up to 100 miles at times...

1)Ionosphere and troposphere delays — The satellite signal slows as it passes through the atmosphere. The GPS system uses a built-in model that calculates an average amount of delay to partially correct for this type of error.

2)Signal multi path — This occurs when the GPS signal is reflected off objects such as tall buildings or large rock surfaces before it reaches the receiver. This increases the travel time of the signal, thereby causing errors.

3)Receiver clock errors — A receiver's built-in clock is not as accurate as the atomic clocks onboard the GPS satellites. Therefore, it may have very slight timing errors.

4)Orbital errors — Also known as ephemeris errors, these are inaccuracies of the satellite's reported location.

5)Number of satellites visible — The more satellites a GPS receiver can "see," the better the accuracy.

6)Buildings, terrain, electronic interference, or sometimes even dense foliage can block signal reception, causing position errors or possibly no position reading at all. GPS units typically will not work indoors, underwater or underground.

7)Satellite geometry/shading — This refers to the relative position of the satellites at any given time.
Ideal satellite geometry exits when the satellites are located at wide angles relative to each other.
Poor geometry results when the satellites are located in a line or in a tight grouping.

8)Intentional degradation of the satellite signal — Selective Availability (SA) is an intentional degradation of the signal once imposed by the U.S. DoD. SA was intended to prevent military adversaries from using the highly accurate GPS signals. The government turned off SA in May 2000, which significantly improved the accuracy of civilian GPS receivers

Not trying to argue that GPS is unreliable... it is very reliable... but situations exist that cause errors... what are the chances of it happening to me?... slim at best... like being in a major car accident... hasn't happened to me in 20 years but I read about it every day so I take action to protect myself.

I heard a comment from an executive that still keeps me on my toes... When dealing with customer issues he was calming down a customer relations manager by saying... "look... The car isn't gonna drive itself into a tree because of a data packet error... it's not like the unit has control of the steering wheel"....

In our case it does have control of the steering wheel and the consequences of a glitch become much more real to us..... :ugeek:
 
Re: Phantom Fly-Aways debunked & possible solutions

MikesTooLz said:
This is exactly why I enabled NAZA mode and test my home location before each flight by flying about 20 feet off and switching S1 all the way down to make sure it comes home correctly, if not I can switch out of RTM and bring it back down.

If the home location happened to be incorrect (and was set 100 m away) isn't switching to RTH (as a test) going to make it piss off over to there? And if it flys away (at this point), switching out of RTH will not save it.
I switched to Naza mode so S1 position 3 is set for manual control (no satellites). Setting it to fail safe/RTH mode duplicates turning off the TX and it will still go where ever it thinks the satellites are telling it to go.

Going into manual mode will be hair raising, but you may have a downed aircraft instead of a lost one.

Just an observation.
(The manual instructs us to flick S2 (left hand switch) up and down 5 times to manually lock the home point, even if it locks automatically) Flicking this in flight to reset home lock is interesting, (if it works, because it IS moving) I'd still rather cut it off from the satellites.
 
Re: Phantom Fly-Aways - Debunking & possible solutions

To manual mode or not manual is the question
 
Interesting theory however, you would see your distance number high on take off. If I take off from somewhere, walk a few hundred feet away while flying. It will show me at a very long distance even though its 10' from me.

I would find it more believable that during flight the GPS suddenly got bad data and thought it had warped into the wrong place and was trying to correct it self. Very similar to the height issue that the video explained about the Parrot.

However, if that was true ... I find it hard to believe that this is something that DJI hasn't caught.
 
The GPS unit in phantoms also utilizing GLONASS sats would stop a lot of the gps related problems. My phone can use them (nexus 4). Maybe the phantom 3? Or possibly a firmware update (cringe)
 
jengo said:
Interesting theory however, you would see your distance number high on take off. If I take off from somewhere, walk a few hundred feet away while flying. It will show me at a very long distance even though its 10' from me.

Walking away has no effect on the display distance... The distance displayed is the distance from P2V+ to home point marked at launch... it is not relative to the controller...

And there are stories of the HUD showing crazy data as the drone flies away... like the couple I read that the red arrow was all the way to the outside of the circle... Also the guy in Hawaii that checked his "find my phantom" right after takeoff while it was hovering right in front of him and it showed the pin 10 miles away from his current location...

Not saying that my story would account for all flyaways but it matches some of the stories so well its like a road map for potential disaster...
 

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