P4P New RTH Features

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I know this has been beat to death but tonight I had my first experience with RTH. I was flying near my house. There is a water tower. On the way out I was a good block to the right of the tower filming a train going down the tracks. Eventually I lost signal and I let the RTH do it's think so I could see how it worked.

It began it's journey home HEADED STRAIGHT for the Water Tower. Luckily I had my RTH altitude set to 500 feet for this very reason, I like to set it for a height that would clear anything in the area I'm flying...so..had I not been at 500 this thing would have smashed right into the tower. When and how is this intelligent return to home executed? I was under the impression it did so on a Loss of Signal RTH...would appreciate any imput..thanks
 
Are you saying it didn't head straight to home?. Because it shouldn't. It should backtrack your course about 30 seconds in an effort to reconnect. If it doesn't reconnect it should then make a beeline to home.


Fly often, be safe
 
Luckily I had my RTH altitude set to 500 feet for this very reason, I like to set it for a height that would clear anything in the area I'm flying...so..had I not been at 500 this thing would have smashed right into the tower.

That shouldn't be "lucky" at all. That is the proper way to configure RTH - for a height that will clear all local obstructions.

Also - RTH doesn't fly back home following the same path it took on the outwards trip. If you activate it manually, or if it's activated due to low battery - it will fly home in a straight line from wherever it happens to be.

I wasn't aware that on signal loss, it would retrace its steps as John Locke reported - but it makes sense to do so if battery levels permit. But even then - I think it will still set a straight line course home if it fails to reconnect.

If you had obstacle avoidance set, it may have navigated around (or over?) the water tower on its own.


Sent from my iPhone using PhantomPilots
 
I know this has been beat to death but tonight I had my first experience with RTH. I was flying near my house. There is a water tower. On the way out I was a good block to the right of the tower filming a train going down the tracks. Eventually I lost signal and I let the RTH do it's think so I could see how it worked.

It began it's journey home HEADED STRAIGHT for the Water Tower. Luckily I had my RTH altitude set to 500 feet for this very reason, I like to set it for a height that would clear anything in the area I'm flying...so..had I not been at 500 this thing would have smashed right into the tower. When and how is this intelligent return to home executed? I was under the impression it did so on a Loss of Signal RTH...would appreciate any imput..thanks
That shouldn't be "lucky" at all. That is the proper way to configure RTH - for a height that will clear all local obstructions.

Also - RTH doesn't fly back home following the same path it took on the outwards trip. If you activate it manually, or if it's activated due to low battery - it will fly home in a straight line from wherever it happens to be.

I wasn't aware that on signal loss, it would retrace its steps as John Locke reported - but it makes sense to do so if battery levels permit. But even then - I think it will still set a straight line course home if it fails to reconnect.

If you had obstacle avoidance set, it may have navigated around (or over?) the water tower on its own.


Sent from my iPhone using PhantomPilots
So if it doesn't follow the outward path on low battery signal
Loss or manual activation when does it follow the return path?
 
So if it doesn't follow the outward path on low battery signal
Loss or manual activation when does it follow the return path?

No problem - I'll repeat myself.

According to John Locke, it follows return path for 30 seconds on signal loss activation.

After that - if it doesn't reconnect successfully - it's a direct path home.

With manual activation of RTH or activation due to battery level, it's a direct path home immediately (after ascending to the configured altitude)

- unless you touch the joystick while it's ascending. If you do, it stops ascending and comes straight home at that height.

- unless you're within 20m of the home point. If you are, the drone will auto-land right where it is.


Sent from my iPhone using PhantomPilots
 
Are you saying it didn't head straight to home?. Because it shouldn't. It should backtrack your course about 30 seconds in an effort to reconnect. If it doesn't reconnect it should then make a beeline to home.


Fly often, be safe
It resented to home beeline. It didn't backtrack
No problem - I'll repeat myself.

According to John Locke, it follows return path for 30 seconds on signal loss activation.

After that - if it doesn't reconnect successfully - it's a direct path home.

With manual activation of RTH or activation due to battery level, it's a direct path home immediately (after ascending to the configured altitude)

- unless you touch the joystick while it's ascending. If you do, it stops ascending and comes straight home at that height.

- unless you're within 20m of the home point. If you are, the drone will auto-land right where it is.


Sent from my iPhone using PhantomPilots

So to sum up the return path is only 30 seconds? Ok. I could have sworn I saw graphics from
Dji showing it following return all the way back. No sure what 30 seconds does for you since if your flying along and lose signal bird can't do much that would cause risk that 30 seconds would erase. In my case the water tower was about 2 minutes in in the Rth that's where I assume trouble would be not 30 sexonds backwards.
 
It resented to home beeline. It didn't backtrack
So to sum up the return path is only 30 seconds? Ok. I could have sworn I saw graphics from
Dji showing it following return all the way back. No sure what 30 seconds does for you since if your flying along and lose signal bird can't do much that would cause risk that 30 seconds would erase. In my case the water tower was about 2 minutes in in the Rth that's where I assume trouble would be not 30 sexonds backwards.

Usually if you lose signal because you flew too far or you flew behind an obstacle, the Phantom wouldn't need to backtrack all the way home to re-establish contact.
Simply coming back from behind the obstacle or back into range should be enough.
And if you had a long windy flight but ended up only 200 yards from home but behind a house, you wouldn't want the Phantom to start going back the long way with a low battery.

The manual is very sketchy when it comes to details of the new backtrack RTH
i-rtRjW5c-M.jpg

The DJI website also says this:
2. How is Phantom 4 Pro’s Smart Return Home improved?
The new Smart Return Home forms a map of its environment in real-time.
The aircraft will choose the best flight path to return home and senses as far as 300m to avoid obstacles more effectively.
If the control signal is lost, the Phantom 4 Pro will retrace its original path to regain its connection after 1-minute.
When it reconnects, it will return to home following a straight route. If it fails to regain connection, it will also revert to straight line RTH.
 
I know this has been beat to death but tonight I had my first experience with RTH. I was flying near my house. There is a water tower. On the way out I was a good block to the right of the tower filming a train going down the tracks. Eventually I lost signal and I let the RTH do it's think so I could see how it worked.

It began it's journey home HEADED STRAIGHT for the Water Tower. Luckily I had my RTH altitude set to 500 feet for this very reason, I like to set it for a height that would clear anything in the area I'm flying...so..had I not been at 500 this thing would have smashed right into the tower. When and how is this intelligent return to home executed? I was under the impression it did so on a Loss of Signal RTH...would appreciate any imput..thanks
Return to home only works if you have it set in your software, check your settings! It also only works if your controller is set to fly in "P" mode. If you are using Litchi Fly or other software make sure your settings are correct to "RETURN HOME" on loss of signal. Remember that loss of signal is not immediate as the drone will wait a few seconds to see if it connects again.
 
Are you saying it didn't head straight to home?. Because it shouldn't. It should backtrack your course about 30 seconds in an effort to reconnect. If it doesn't reconnect it should then make a beeline to home.


Fly often, be safe
John is 100% correct. See this video here to see how the "lost signal" back track works.

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The DJI website also says this:
2. How is Phantom 4 Pro’s Smart Return Home improved?
The new Smart Return Home forms a map of its environment in real-time.
The aircraft will choose the best flight path to return home and senses as far as 300m to avoid obstacles more effectively.
If the control signal is lost, the Phantom 4 Pro will retrace its original path to regain its connection after 1-minute.
When it reconnects, it will return to home following a straight route. If it fails to regain connection, it will also revert to straight line RTH.
To add to this, you have to enable OA during RTH in the settings for this part of it. It is NOT able to do this by default. It uses the primary camera on the gimbal to do this.
 

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I don't understand why it can't trace back all the way if needed.
Most of the time it won't be needed ... just going back 20 feet or so should reestablish contact.
You definitely don't want your Phantom to backtrack 100% by default.
Having the option to only go a short distance or 100% would be too complicated and definitely cause problems in some situations.
Maybe there's a memory limitation to how far they can store a track?
 
Most of the time it won't be needed ... just going back 20 feet or so should reestablish contact.
You definitely don't want your Phantom to backtrack 100% by default.
Having the option to only go a short distance or 100% would be too complicated and definitely cause problems in some situations.
Maybe there's a memory limitation to how far they can store a track?
This is true...
 
Most of the time it won't be needed ... just going back 20 feet or so should reestablish contact.
You definitely don't want your Phantom to backtrack 100% by default.
Having the option to only go a short distance or 100% would be too complicated and definitely cause problems in some situations.
Maybe there's a memory limitation to how far they can store a track?

It's not a memory limitation. The internal SD card they write the logs to has plenty of room to store dozens of flights - including the GPS co-ordinates every second of the way.

It's far more likely that they decided it's not useful to backtrack the entire way. It's designed to kick-in on signal loss. If you had a signal up to a moment ago, backtracking for a few seconds will be enough to get the signal back at which point the pilot can resume flying. If that doesn't work, the shortest, most direct path home is almost always the best choice.


Sent from my iPhone using PhantomPilots
 
Last edited:
Great explanation, thanks F3. I'm a noobie P4P owner, arrives tomorrow and I am reading and watching all I can to not make a fatal mistake. This is great!


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