What's the difference between "Smart" & "Failsafe" RTH?

[msinger]

including a video I posted recently

Got a link?

 

[John Locke]

I really feel a lot of the above is not correct.
I have never read in any documentation that the Phantom will RTH by retracing it's recent course under any circumstances. After reading the manual, this is what I understand.
“Smart Return Home” denotes that the remaining battery capacity can only support the aircraft from return to the home point from the current position hence the app will prompt a message to notify that RTH is being invoked to bring the aircraft back to the home point at that moment. Object avoidance is active. You can cancel if you don’t want this to activate.
"Failsafe Return Home" will do the same as above, except it is invoked upon signal loss of 3 seconds or more duration.

Page 15 of the P4P user manual says:

 

[F3honda4me]

Got a link?

From 27 seconds to about 50 seconds I had no TX connection and the bird backtracks instead of beeline straight home. Please note the video was to demonstrate an RTH ascent bug for DJI but you can see the backtrack work.

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[msinger]

Thanks!

 

[GeoffJ]

Ah, that's not retracing its course to home. That does sound reasonable if it just moves back a little to try to regain the signal, but I haven't heard of that before.
I think this is the best information I can find in DJI Documentation.

SMART RTH
RTH initiates when the Phantom thinks it might have trouble getting home taking into account rising to the RTH height, and flying from its current location to the Home Point.
It takes a very conservative approach. You can manoeuvre the drone using the sticks on the return trip. Object avoidance is switched on.
You can cancel the function if you choose within 10 secs.

LOW BATTERY RTH
usually initiates at 30% battery, but you can set the threshold yourself.
Everything else as for SMART RTH

FAILSAFE RTH
Activates when the Remote Controller signal is lost for 3 or more secs.
Everything else then as for Smart RTH. It keeps returning home after signal is reconnected unless you cancel it.

BUTTON RTH
Activated by pressing the Remote Control RTH button, Then as for Smart RTH

EMERGENCY Low Battery Landing
When the battery gets to the emergency setting (5 or 10% usually, you set this), it will go into Auto land status. You can still manoeuvre it during the landing.

 

[GeoffJ]

Please note the video was to demonstrate an RTH ascent bug for DJI but you can see the backtrack work.

Can you show us the recorded log so we can see what it was actually doing? You don't really know from this what was happening.

 

[msinger]

GeoffJ, I realize you're trying to be helpful, but you're actually adding more incorrect information than what was stated previously.

FYI, in your descriptions above, "SMART RTH" and "BUTTON RTH" are the same thing. I know it's confusing, but "Smart RTH" is not the same thing as "Smart Return-to-Home" (which is not covered in the Phantom manual).

 

[F3honda4me]

Can you show us the recorded log so we can see what it was actually doing? You don't really know from this what was happening.

Since there was no TX signal there is nothing during this timeframe in the log from the TX for me to share. Also did you miss the part in the manual under failsafe where it talks about retracing? I'm not sure why you are refusing to acknowledge this feature exists.

 

[GavinW]

Wow, so DJI might have been lying about RTH backtracking?

 

[GeoffJ]

I know it's confusing, but "Smart RTH" is not the same thing as "Smart Return-to-Home" (which is not covered in the Phantom manual).

Please explain then, happy to be corrected.
It would be good to get this nailed down once and for all as it keeps cropping up.

 

[GeoffJ]

I'm not sure why you are refusing to acknowledge this feature exists.

I don't think I said that, but I am keen to see what happened. I haven't heard this mentioned before and it would be good to understand what happens. It would be interesting to just have a drone flying past not too far away and then just turn the controller off to see what happens.

 

[msinger]

Smart RTH: When you manually activate RTH by holding the button on the remote controller or by clicking the RTH icon on the left side of DJI GO.

Smart Return-to-Home: When your Phantom auto initiates RTH when it calculates it needs to turn back in order to make it home before the battery dies.

 

[F3honda4me]

I don't think I said that, but I am keen to see what happened. I haven't heard this mentioned before and it would be good to understand what happens.

On the rc groups thread there are DJI staff who post. They are the ones who verified the 60 seconds. I've explained exactly how the retracing works so you know what happens. Test it yourself if you like. It's easy to test.

 

[John Locke]

Wow, so DJI might have been lying about RTH backtracking?

This seems pretty clear on Page 15 of the manual saying the craft will "...retrace it's original flight route home".

The video in post #23 showed the craft retracing it's original route, so it appears clear this feature exists and it works, somewhat. There seems to be a bug in the firmware making the craft gain altitude during the RTH, obviously something that needs fixed. That's not suppose to happen.

 

[GeoffJ]

That's certainly not what the latest Version of the manual Ver 1.2, available on the DJI web site says.
There are plenty of videos where the signal has been lost and the Failsafe Return takes a direct route home from where the signal was lost.
The increase in height when RTH is activated is normal if the bird is flying lower than the set RTH height in the settings. It will pause, rise to the set height, then go directly home.

Check your manual version, it might be an old one. That is clearly not in the current one which you can download here.
https://dl.djicdn.com/downloads/phantom_4/en/Phantom_4_User_Manual_en_v1.2_20160805.pdf

 

[GeoffJ]

I was able to find this video which is a guy testing Failsafe RTH on a P4.
Although he nearly crashed into trees a few times on the way to the point where he turned off the controller and sent it home, you can easily see it didn't follow the roads he took, but went directly home.

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[msinger]

GeoffJ, you do realize you're posting in the P4P forum, right? The manual and video you linked above are for the P4.

 

[GeoffJ]

GeoffJ, you do realize you're posting in the P4P forum, right? The manual and video you linked above are for the P4.

My apologies, no I hadn't noticed that this was P4P.

Irrespective however, it's difficult to believe they would change the strategy of this basic function, and it will be interesting to see the results of a simple test.
If someone could just fly off for 150 metres or so, go a similar distance at right angles, and then turn off the controller, we should have a clear result.

 

[F3honda4me]

My apologies, no I hadn't noticed that this was P4P.

Irrespective however, it's difficult to believe they would change the strategy of this basic function, and it will be interesting to see the results of a simple test.
If someone could just fly off for 150 metres or so, go a similar distance at right angles, and then turn off the controller, we should have a clear result.

The backtrack is only available on the p4p. The p4 does not have this feature. The p4p is a very different craft. I have owned both. My video clearly shows my aircraft backtracking a good 30 seconds.

 

[Jase1125]

My apologies, no I hadn't noticed that this was P4P.

Irrespective however, it's difficult to believe they would change the strategy of this basic function, and it will be interesting to see the results of a simple test.
If someone could just fly off for 150 metres or so, go a similar distance at right angles, and then turn off the controller, we should have a clear result.

So it's easier to believe that DJI doesn't make changes to their aircrafts, gives them a new names and marks up the price? As stated the new function has demonstrated and also documented in the P4P manual.