RTH along intelligent path

[qtonic]

I recall a lot of hype around the extra smart RTH functions when the P4P was launched. I don't remember what they call it, but the idea is that sometimes the aircraft can return along it's original path instead of in a straight line at a given altitude.

Lately I don't see much discussion of this. What are the thoughts on it? Any recent videos covering it?

 

[lickitysplit11111]

I recall a lot of hype around the extra smart RTH functions when the P4P was launched. I don't remember what they call it, but the idea is that sometimes the aircraft can return along it's original path instead of in a straight line at a given altitude.

Lately I don't see much discussion of this. What are the thoughts on it? Any recent videos covering it?

I was told early on that it only retraces its path for a few seconds to try to regain the lost signal and if it cannot regain it it then makes a straight line home, but it f you were under the impression that it follows its original flight path your we're mistaken

 

[MaxHam]

It actually does retrace it's path back when the vision system was activated:

Failsafe RTH
The Forward Vision System allows the aircraft to create a real-time map of its flight route as it flies. If the
Home Point was successfully recorded and the compass is functioning normally, Failsafe RTH will be
automatically activated if the remote controller signal is lost for more than three seconds. The aircraft
will plan its return route and retrace its original flight route home.

 

[qtonic]

My impression is that most people have the vision position system active, yet I don't hear many things about this RTH behavior.

I'm confused and can't currently go test it myself, unfortunately.

 

[Meta4]

It's the default action for loss of signal and the Phantom will retrace its track to regain signal.
It can be very handy if you fly behind an obstacle.

 

[qtonic]

I read about auto landings when a RTH path would cross an NFZ. I think that behavior may be changed now, but is it true that that would not have happened with this Failsafe RTH? In other words, if it backtracks the flight, then it would have no need to return across an NFZ.

Also, what happens if for some reason signal is never regained? (Maybe controller battery, hypothetically)

Does it just keep tracing back a potentially long, complicated flight path? What if part of that path went right by the home point? And does the part of the system that calculates how much battery is needed to get home take into account the entire flight path up to that point? Seems like theoretically that would necessitate pretty early auto RTH if not based on actual distance from home.

Sorry for all the questions, but I have a feeling this behavior/feature likely has some caveats and I like to understand how something actually works, not just how it's listed in a brochure.

 

[smiller]

Does it just keep tracing back a potentially long, complicated flight path?

No, it does not trace the exact flight path all the way back to the home point. Failsafe RTH backtracks for a limited time/distance in an attempt to regain contact with the controller. If it cannot then a normal (beeline at preset RTH altitude) RTH will be performed.

 

[John Locke]

No, it does not trace the exact flight path all the way back to the home point. Failsafe RTH backtracks for a limited time/distance in an attempt to regain contact with the controller. If it cannot then a normal (beeline at preset RTH altitude) RTH will be performed.

Yes, that's my understanding too.

The manual is not very clear on this IMO. It talks about a 10 second pause, without clarification.

I haven't known anyone to test this yet, but I think what occurs is when the craft loses signal, is stops motion like normal for 3 seconds, then goes into this new "SMART RTH", assuming no signal is regained. At this point the "SMART RTH" enables and the craft to retrace it's path backwards. But, everyone wants to know, how far does it retrace the path? The answer is, until a connection is re-established with the RC, up to 1min of travel (I think). Theoretically it shouldn't take very long for the craft to regain a connection with the RC if it retraces it's path, assuming the pilot hasn't moved. Then, when a signal is regained, the craft will stop for 10 seconds (interrupting RTH travel, per manual) and give the pilot the opportunity to retake control. The LED light on the RC will turn from RED to GREEN, indicating a link has been re-established. After 10 seconds being reconnected, if the pilot doesn't retake control, I think the craft makes a beeline for home from that point, like in the past. Since a link has been established during this beeline RTH, the pilot can take over control at any time.

What if a link isn't re-established during SMART RTH? I believe the craft will retrace is path for up to one minute (that's what I recall anyway), then if no connection is made during that 1 minute, the craft changes RTH mode and will make a straight beeline to home. What would be really SMART, would be for the craft to always enable OA in these scenarios (if OA is disabled during the flight), but we're not there yet.

 

[axelz]

I also read on this forum that apparently during smart rth it will only retrace for up to a minute in order to regain signal to remote - DJI support had confirmed apparently, though later firmwares now so no idea if still stands or indeed did to start with. Agree their docs are a bit vague!