RTH: How It Works and What to Avoid

Mark The Droner

Labroides Posted at 2018-6-26 15:33
It's unlikely the Phantom could get 60m high and 180 metres out without getting GPS and recording a homepoint.
But if it did happen, I guess that could explain the failure to come home.

Once I had my P2V mark a homepoint behind me in the woods several hundred feet. And I didn't notice it until several months later when I went over the log. It only happened that once that I know of out of several hundred flights. I have no explanation. Also, sometimes when you're watching the AC and it's in RTH, it looks like it's hovering but actually it's slowly rising to min RTH height first, so you think it's not RTHing when actually it is. But the log wouldn't help us there.

Suren

Mark The Droner Posted at 2018-6-26 11:03
Please upload and post the link: http://www.phantomhelp.com/LogViewer/Upload/

I looked at the log and it just ends when the RC disconnects does not say much about why it did not work

Suren

Labroides Posted at 2018-6-26 14:38
Unfortunately his flight data would only show what happened before switching off the controller.
What happened after that would be the interesting part.

That is correct, already looked at log, it should have intiated rth when rc disconnected

Suren

Labroides Posted at 2018-6-26 14:40
That's sounds unusual. The first time I've heard of it
Just the one test?
You definitely switched off the controller - not just the display?

Put the rc completely off, when i manually press the rth it works though

Suren

Mark The Droner Posted at 2018-6-26 15:29
I wanted to see where the homepoint was recorded

Homepoint was recorded correctly because when rc was powered on again i hit the rth manually and it came home, as I said was only 60 meters high and 150 meters away to test this

Suren

Labroides Posted at 2018-6-26 15:33
It's unlikely the Phantom could get 60m high and 180 metres out without getting GPS and recording a homepoint.
But if it did happen, I guess that could explain the failure to come home.

full gps 12 sats and my little friend said "your home point has been recorded"

Mark The Droner

What is your min RTH height, what was your actual height? Could you post the log?

solentlife

Labroides Posted at 2018-6-26 14:32
Sorry ... bad subject to pick with me ...
That's one thing I can agree with you on.
There's nothing anyone can tell you about GPS

Your choice L ...

Having had to put my life on the reliability and accuracy of GPS on more than one occasion - I know the reality of Military vs Publicly available GPS.

Its not only Military Personnel that go into areas of extreme ... want to trust a Garmin or TomTom in that ???

For practical purposes and the algorithms used in modern consumer units - they perform excellently. The user is unaware of the variables it is discarding etc.

But never confuse that with the higher precision / better algorithm military units.

Nigel

solentlife

Labroides Posted at 2018-6-26 14:38
Unfortunately his flight data would only show what happened before switching off the controller.
What happened after that would be the interesting part.

What about the on-board data file ?

Nigel

solentlife

Suren Posted at 2018-6-26 19:24
Put the rc completely off, when i manually press the rth it works though

Something definitely not right now ... there should be no way the RTH button can work if Controller is powered OFF. Where would the signal be generated from ??
Now looking at your later post - I think you meant to say :

RTH did not work when Controller switched off ... but once you powered controller again - it worked ??

Nothing wrong with that - the AC records the RTH position - not the controller or tablet. Just strange that the AC did not RTH when you powered down ...

Have you re-checked all SMART and FAILSAFE settings .. ?? Made sure you really have RTH as the set option and not just Hover ?

Nigel

Mark The Droner

solentlife Posted at 2018-6-27 02:19
Something definitely not right now ... there should be no way the RTH button can work if Controller is powered OFF. Where would the signal be generated from ??
Now looking at your later post - I think you meant to say :

I think you need to read post #171 again, coupled with post #182.

Mark The Droner

Suren Posted at 2018-6-26 19:25
Homepoint was recorded correctly because when rc was powered on again i hit the rth manually and it came home, as I said was only 60 meters high and 150 meters away to test this

This is part of the problem. You never said it was 150 meters away. You said it was 180 meters away. Now you say it was 150 meters away? Was it 150 or 180? Maybe it was actually only 120 meters away? How do we know? We have to take your word for it.

Why not post the log? It takes less than 30 secs. http://www.phantomhelp.com/LogViewer/Upload/

Labroides

solentlife Posted at 2018-6-27 02:15
Your choice L ...

Having had to put my life on the reliability and accuracy of GPS on more than one occasion - I know the reality of Military vs Publicly available GPS.

Yeah Nigel ... So that's compasses and GPS now
No-one else has ever used GPS before
You're the only person that knows anything about GPS
... as you showed in post #162 where you posted a whole essay to waffle about what had already been answered in two lines in post #160 hours earlier.
We bow to your amazing knowledge

solentlife

Mark The Droner Posted at 2018-6-27 03:11
I think you need to read post #171 again, coupled with post #182.

No .. I have already .. and he posted 181 with the powered off but RTH working !! Which the three posts taken as posted do not add up.

Also it seems to indicate that he's surprised RTH was still available when he powered back up.

I just have a feeling that somethings not being admitted to ??

Just trying to think why the AC would hover and not RTH. Only instance I have seen that is when my P3 had the tablet shut down but RC was still on and connected. I let go sticks so AC would not fly off into unknown ... it hovered ... I hit RTH on RC and she came back ... while I restarted tablet.
If the RC had gone off - the AC would have RTH'd. Unless option to Hover had been selected instead.

Nigel

Mark The Droner

As we all know, these things turn out to be pilot error 98% of the time - or more. Some solid info would be nice.

solentlife

Labroides Posted at 2018-6-27 03:17
Yeah Nigel ... So that's compasses and GPS now
No-one else has ever used GPS before
You're the only person that knows anything about GPS

Yes L ... sure ..... you know best.

Iran - Iraq Conflict
Gulf War 1
Afghanistan

Yes .. and a few other minor conflicts as well ... you'd be surprised how much a Civilian like me has to do in such ... my life is worth more than trusting to your interpretations. Sorry if blunt - but its fact.
I didn't see you on the front line xxxx xxxxx xxxxx from Kuwait ... xxxxx me at the small crossing point ..

Didn't see you setting up the fuel dumps for forward units...

Lives depended on it .... like I say - didn't see you there.

Nigel

Edited out confidential data

solentlife

''as you showed in post #162 where you posted a whole essay to waffle about what had already been answered in two lines in post #160 hours earlier.''

Go back and he actually asked more than just SA .. he mentioned the Airport Augmentation as well ... my 'waffle' as you put it supplies the answer and explanation of why / what it was ... some people like to know more than just a piffling bit of a very interesting subject.

Nigel

solentlife

Just to nail the lid on your coffin L :

''We bow to your amazing knowledge''

You can't even get the name right !!
Dunno where you get the term Selective Accuracy from because its always been Selective Availability .... because it was not only the degradation of info - but also the ability to switch it off .... Availability.

Please see :

https://www.gps.gov/systems/gps/modernization/sa/

There is one aspect of SA that is still there ... which is not mentioned in the Gov Doc for good reason - switch Off capbility ... plus degradation is still possible - you only have to ask users in vicinity of Military Exercises ... check out Marine Notice to Mariners etc. warning of GPS 'disruption' not only by local means but also via the actual sats themselves.

Bye L ... you astound me at times ...

Nigel

Labroides

solentlife Posted at 2018-6-27 03:35
Yes L ... sure ..... you know best.

Iran - Iraq Conflict

You can't even get the name right !!
Dunno where you get the term Selective Accuracy from because its always been Selective Availability
Big deal ... it was 20 years ago and I made a minor slip up on the wording.
Enjoy it, you don't get that opportunity very often.

Yes .. and a few other minor conflicts as well ... you'd be surprised how much a Civilian like me has to do in such ... my life is worth more than trusting to your interpretations. Sorry if blunt - but its fact.
I didn't see you on the front line xxxx xxxxx xxxxx from Kuwait ... xxxxx me at the small crossing point ..

Didn't see you setting up the fuel dumps for forward units...
Lives depended on it .... like I say - didn't see you there.

I didn't see you anywhere that I was either
But now I understand why you're the only person that knows anything about GPS.

ps ... WTF does any of that have to do with anything on this forum?

Labroides

Suren Posted at 2018-6-26 19:24
Put the rc completely off, when i manually press the rth it works though

Put the rc completely off, when i manually press the rth it works though .
Can you clarify the timing for this?
Is there any chance that you switched off and a couple of seconds later pressed RTH and saw the drone begin to RTH .... as it would normally a few seconds after switching off?

Have you tested this multiple times to see if it's an ongoing and repeatable issue or just a one-off?

KedDK

Lol 3 pages and a bit in 2½ year now soon the same on a day.

What does civil contra military precision have to do with RTH and the strange behavior about not performing a RTH within 20 meters in the first place?
If the aircraft know it has moved 20 meters away from the HP, for sure it should be able to fly 20 meters back whether i would take detour to RTH altitude or not on the way, just imo.

Suren

solentlife Posted at 2018-6-27 02:19
Something definitely not right now ... there should be no way the RTH button can work if Controller is powered OFF. Where would the signal be generated from ??
Now looking at your later post - I think you meant to say :

Hi Nigel, RTH did not work when Controller switched off ... but once you powered controller again - it worked ?? Yes you are correct guess my wording came out wrong

Suren

solentlife Posted at 2018-6-27 02:19
Something definitely not right now ... there should be no way the RTH button can work if Controller is powered OFF. Where would the signal be generated from ??
Now looking at your later post - I think you meant to say :

All failsafe settings have been checked and verfied as well

solentlife

Suren Posted at 2018-6-27 08:54
Hi Nigel, RTH did not work when Controller switched off ... but once you powered controller again - it worked ?? Yes you are correct guess my wording came out wrong

Thank you ...

As another asked - how long did you wait before deciding RTH was not working ?

At 150 or 180m out and 60m high ... it would be difficult to visually confirm RTH until a significant time / distance covered by AC ... the height and distance angle makes for poor visual / spacial judgement.

I think a better test would be to find a nice open clear area and perform a flight out past 20m ... lets say go out about 50 - 75m .... but stay relatively low - well under your RTH set height.

THEN try it again ... switch of controller.

This way being more lower, not so far away - you will have much better visual to see if it works or not.
It should stop ... hover a few seconds .... then ascend to RTH height you set ... then turn and fly back to be vertically over Home Point ... then descend vertically to land ...

I strongly suggest you take over to manually land once you confirm it is all working as it should to avoid the 'tip-over' blues !!

Nigel

Suren

Mark The Droner Posted at 2018-6-27 03:16
This is part of the problem. You never said it was 150 meters away. You said it was 180 meters away. Now you say it was 150 meters away? Was it 150 or 180? Maybe it was actually only 120 meters away? How do we know? We have to take your word for it.

Why not post the log? It takes less than 30 secs. http://www.phantomhelp.com/LogViewer/Upload/

To me it seemed so, I dont take likely to guys saying to prove things. The log is below and the distance is not the concern to me what does concern me is why the RTH did not kick in on full disconnect of the RC which it should have. I have alot of meters behind me and Pilot error for me is something that I will ensure does not happen hence me trying all these tests close by before building trust in the drone. I have done the exact same tests with my Mavic Pro and it worked all the time. I like to know that the drone is stable enough to go the miles and return back safely as these things dont come cheap especially here in RSA. This seems to be the correct log for that flight

This is the log after re-connect http://www.phantomhelp.com/LogViewer/WZ4RSTCCRBYHRIX3C8LV/

this is the Log on disconnect http://www.phantomhelp.com/LogViewer/MPMPK77TUTCR64V72X3T/

Suren

solentlife Posted at 2018-6-27 03:27
No .. I have already .. and he posted 181 with the powered off but RTH working !! Which the three posts taken as posted do not add up.

Also it seems to indicate that he's surprised RTH was still available when he powered back up.

Just to clear up some confusion, i intiated the rth on re-power up of the rc, when it showed connect again after powering up RC again the rth worked when manually selecting it. I did not hit rth when it was off, my wording came out wrong

Suren

Mark The Droner Posted at 2018-6-27 03:32
As we all know, these things turn out to be pilot error 98% of the time - or more. Some solid info would be nice.

Doubt you can call testing the RTH feature a Pilot Error

Suren

Labroides Posted at 2018-6-27 04:51
Put the rc completely off, when i manually press the rth it works though .
Can you clarify the timing for this?
Is there any chance that you switched off and a couple of seconds later pressed RTH and saw the drone begin to RTH .... as it would normally a few seconds after switching off?

Tested just once only, I had updated the app before this test so going to roll back and check if it works. The drone did not RTH when RC was off just stayed there hovering

Suren

solentlife Posted at 2018-6-27 09:08
Thank you ...

As another asked - how long did you wait before deciding RTH was not working ?

Thanks for the advise and tip, will try that. I posted the flight logs of after disconnect and before as well

Suren

If you look at both the flight logs you will see that the drone disconnected at 10m:55 seconds and reconnected at 11m:23 seconds +/-.

Mark The Droner

There are a lot of oddities about the flight - but nothing that has anything to do with the RTH not working with loss of signal. The data shows the AC didn't move an inch after the signal loss. I don't know what the explanation is unless you had it set to hover upon loss of signal. Good luck.

Suren

Mark The Droner Posted at 2018-6-27 09:41
There are a lot of oddities about the flight - but nothing that has anything to do with the RTH not working with loss of signal. The data shows the AC didn't move an inch after the signal loss. I don't know what the explanation is unless you had it set to hover upon loss of signal. Good luck.

As mentioned it was set to RTH. this was checked before the disconnect test and after reconnecting again. This is one of my pre-flight checks that get done everytime I fly.

solentlife

I know you say you checked settings for RTH ...

But let me mention one thing : It is not unknown that after updating any part .. FW / GO etc. - that user settings revert to factory and you have to go in and physically reset your own. This has caught out a few people ..

nigel

Suren

solentlife Posted at 2018-6-27 10:21
I know you say you checked settings for RTH ...

But let me mention one thing : It is not unknown that after updating any part .. FW / GO etc. - that user settings revert to factory and you have to go in and physically reset your own. This has caught out a few people ..

Noted

Labroides

Suren Posted at 2018-6-27 10:30
Noted

If an update changed the Loss of Signal action to the default value, that is RTH.
It's very rare that anyone ever changes this setting.
RTH is baked into the Phantom firmware so messing around with the app version shouldn't make any difference
.... particularly when the controller is switched off !!

You've reported unusual RTH behaviour on one occasion.
To get this sorted out, you need to do some testing to establish whether this is repeatable.
If you fly out 50 metres and switch off five times, what happens?

Mark The Droner

There are quite a few things about the log that bug me which isn't exactly on topic but it still bugs me. This is one of them: Please see the log a 0m 4.6 secs

http://www.phantomhelp.com/LogViewer/MPMPK77TUTCR64V72X3T/

He has 7 satellites in a GPS/Glonass system and yet he is in P-GPS mode which means he as a satellite fix. And according to post #168, the OP must have either 6 GPS satellites and 1 GLONASS satellite. Or he has 7 GPS satelites and 0 GLONASS satellites. Or vice versa. This doesn't make sense to me. I never realized there was such a huge discrepency between the visible GPS satellites vs the visible GLONASS satellites. Comments?

Labroides

Mark The Droner Posted at 2018-6-27 17:17
There are quite a few things about the log that bug me which isn't exactly on topic but it still bugs me. This is one of them: Please see the log a 0m 4.6 secs

http://www.phantomhelp.com/LogViewer/MPMPK77TUTCR64V72X3T/

That's not a big concern.
His Phantom acquired a good GPS fix and recorded home point with 9 sats.
It held 9 sats but from 3.6 sec to 4.9 sec this dropped to 8 with 0.2 sec of 7 sats.
Seven may or may not have been enough to provide a good fix but if not, the Phantom, like most GPS receivers avoids dropping in and out by smoothing things a little.
It takes a sustained drop in sat numbers, maybe a few seconds (not sure of the time required) before it gives up and drops to atti.

To investigate further, find a flight log where you fly under a roof and check when the flight mode drops out of P-GPS against the sat numbers.

Suren

Labroides Posted at 2018-6-27 13:54
If an update changed the Loss of Signal action to the default value, that is RTH.
It's very rare that anyone ever changes this setting.
RTH is baked into the Phantom firmware so messing around with the app version shouldn't make any difference

Have to test that theory

Labroides

Suren Posted at 2018-6-27 19:31
Have to test that theory

It's not a theory.
It should be obvious that when you kill the controller, the Phantom is left on its own and has no way to get anything from the app or controller.
Whatever it does about RTH is what's in the Phantom.
It couldn't work any other way.

KedDK

Suren Posted at 2018-6-27 09:30
If you look at both the flight logs you will see that the drone disconnected at 10m:55 seconds and reconnected at 11m:23 seconds +/-.

No that figures only tell you when it stopped logging and started logging again. You would have to pull the flight log from the aircraft to see what actually was going on seen from the aircrafts point of view.
As i told you in your own thread, i simply think you have missed how long time it takes before the connection get cut and how fast it comes back when you restart the controller.