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Lost Signal RTH, From The DRONE Point of View!

Chaosrider

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I’ve been tempted to do an intentional lost signal RTH for some time now, but I haven’t quite been able to work up the nerve to do it. Now Reliant, my Mini-1, has done it for me.

I’ve settled on a standard “qualification” for testing new drones in my somewhat challenging mountain flying environment. It’s pretty simple: Is the drone stable with a reliable signal at 2000 ft away, and at 1000 ft ATL? My canyon environment makes it easy for me to get 1000 ft ATL while remaining below 400 ft AGL at all points in the flight.

Reliant passed her distance qual early, although the signal strength is a bit shaky compared to the Mini-SE, and not close to comparable to the Mini-2. But Reliant’s altitude qual has been more elusive…uncooperative winds.

Reliant was the 4th of my 5 Minis to fly during the Easter Sunday Marathon, and I really wanted to get that altitude qual done. But at a measly 350 ft ATL, I got a high wind warning. So I reduced altitude and waited for a bit, but when I tried again I got the same warning. I finally gave up, and decided to bring her back to play close to home instead. I dropped the altitude twice more in response to high wind warnings.

There is, of course, a trade-off between altitude and control signal quality, all other things being equal. Very broadly, the higher you are, the better the control signal quality, because you get farther away from ground clutter.

I was doing a relatively low local cruise, when I got the high wind indication again. I dropped again, and figured it was time to come home. That’s when the fun started. Check out this video:

22-04-07 Lost Signal RTH Mini-1.mp4

00:00 The video starts after I reduce altitude after the high wind warning, and start to come back home. When you get a high wind warning, it also tells you that it can’t come home automatically, but that’s not entirely true…

00:15 Note that the drone stops moving. At that point I get a low signal alert, and Reliant says that she’s not going to send me any more video, and that she’s coming home. Note that there was no reduction in the RC signal strength indicator in Fly prior to this warning. Five bars good, and then dead. Everything Reliant does after that, is on her own, with no control input from me. It is a very weird and disconcerting feeling to know that your drone is doing something, but you can’t see any data from the drone. No video, nothing.

00:23 Reliant makes her turn to come home.

00:29 Reliant starts to climb to her assigned RTH altitude. Highly problematic! I’d been flying low to avoid the winds, and she was going up to meet the Monster. I also hadn’t accounted for that climb in my power management plan, which will now be amended accordingly.

00:42 A strange sequence of events begins. Reliant rotates left for some reason beyond my understanding. Note also that I have the camera in FPV mode, so you can actually see the effects of the Wind Monster.

00:47 Reliant is coming home, obviously fighting the wind valiantly, but she’s pointed at 90º left of her direction of motion. I had nothing to do with that choice of orientation.

01:23 The signal is reacquired. At this point, the home point is about 120º left of the nose. As I’m bringing her home, I now get a low power warning! The combination of fighting the wind, and the unplanned climb, had burned up my power reserves. At that point we were in danger from an Attack of the RTH! But I was able to cancel a couple of those warnings, and land normally with about 1:30 minutes left on the battery, well below my normal landing levels.

Obviously, anyone who says a Mini-1 can’t handle anything other than a light breeze, is badly misinformed!

It's not just flying a drone; it’s an adventure!

1650649462891.png

MM…FP..?
 
I’ve been tempted to do an intentional lost signal RTH for some time now, but I haven’t quite been able to work up the nerve to do it.
Testing failsafe behaviour is a simple matter only requiring that you go to a large, open area, fly 100 feet away and turn off the controller.
Much better to do that in controlled conditions and know what happens, than to wonder about it and have to find out in a difficult situation.
Obviously, anyone who says a Mini-1 can’t handle anything other than a light breeze, is badly misinformed!
On its original firmware, the Mini wasn't able to handle anything other than a light breeze.
In RTH its speed was very slow and dealing with more than a light breeze often resulted in loss of the Mini.
DJI was forced to address this shortcoming with firmware that increased the pitch angle in RTH situations where the drone wasn't able to make headway.
With this the Mini can pitch up to the same angle as it uses for Sport Mode.
But the Mini is still the slowest Mavic with a top speed of 13 metres/sec and the one that will be most affected by wind and least able to fight it.
 
On its original firmware, the Mini wasn't able to handle anything other than a light breeze.
In RTH its speed was very slow and dealing with more than a light breeze often resulted in loss of the Mini.
Ahh, that could explain a lot.

So, the Mini-1 was originally terrible at handling the wind, but then got better through firmware updates. Am I reading what you're saying correctly?
But the Mini is still the slowest Mavic with a top speed of 13 metres/sec and the one that will be most affected by wind and least able to fight it.
That's consistent with my test results. The Mini-SE is better than the Mini-1 in this regard, and the Mini-2 is vastly better than either of them.

Thx!

:)

MM...FPV?
 
I’ve been tempted to do an intentional lost signal RTH for some time now, but I haven’t quite been able to work up the nerve to do it. Now Reliant, my Mini-1, has done it for me.

I’ve settled on a standard “qualification” for testing new drones in my somewhat challenging mountain flying environment. It’s pretty simple: Is the drone stable with a reliable signal at 2000 ft away, and at 1000 ft ATL? My canyon environment makes it easy for me to get 1000 ft ATL while remaining below 400 ft AGL at all points in the flight.

Reliant passed her distance qual early, although the signal strength is a bit shaky compared to the Mini-SE, and not close to comparable to the Mini-2. But Reliant’s altitude qual has been more elusive…uncooperative winds.

Reliant was the 4th of my 5 Minis to fly during the Easter Sunday Marathon, and I really wanted to get that altitude qual done. But at a measly 350 ft ATL, I got a high wind warning. So I reduced altitude and waited for a bit, but when I tried again I got the same warning. I finally gave up, and decided to bring her back to play close to home instead. I dropped the altitude twice more in response to high wind warnings.

There is, of course, a trade-off between altitude and control signal quality, all other things being equal. Very broadly, the higher you are, the better the control signal quality, because you get farther away from ground clutter.

I was doing a relatively low local cruise, when I got the high wind indication again. I dropped again, and figured it was time to come home. That’s when the fun started. Check out this video:

22-04-07 Lost Signal RTH Mini-1.mp4

00:00 The video starts after I reduce altitude after the high wind warning, and start to come back home. When you get a high wind warning, it also tells you that it can’t come home automatically, but that’s not entirely true…

00:15 Note that the drone stops moving. At that point I get a low signal alert, and Reliant says that she’s not going to send me any more video, and that she’s coming home. Note that there was no reduction in the RC signal strength indicator in Fly prior to this warning. Five bars good, and then dead. Everything Reliant does after that, is on her own, with no control input from me. It is a very weird and disconcerting feeling to know that your drone is doing something, but you can’t see any data from the drone. No video, nothing.

00:23 Reliant makes her turn to come home.

00:29 Reliant starts to climb to her assigned RTH altitude. Highly problematic! I’d been flying low to avoid the winds, and she was going up to meet the Monster. I also hadn’t accounted for that climb in my power management plan, which will now be amended accordingly.

00:42 A strange sequence of events begins. Reliant rotates left for some reason beyond my understanding. Note also that I have the camera in FPV mode, so you can actually see the effects of the Wind Monster.

00:47 Reliant is coming home, obviously fighting the wind valiantly, but she’s pointed at 90º left of her direction of motion. I had nothing to do with that choice of orientation.

01:23 The signal is reacquired. At this point, the home point is about 120º left of the nose. As I’m bringing her home, I now get a low power warning! The combination of fighting the wind, and the unplanned climb, had burned up my power reserves. At that point we were in danger from an Attack of the RTH! But I was able to cancel a couple of those warnings, and land normally with about 1:30 minutes left on the battery, well below my normal landing levels.

Obviously, anyone who says a Mini-1 can’t handle anything other than a light breeze, is badly misinformed!

It's not just flying a drone; it’s an adventure!

View attachment 147126

MM…FP..?
late to the party but ive aaccidentally done it, flew it out 1km to a river, lost signal, it turned around and flew back to around 300m and then I took manual control.
 
late to the party but ive aaccidentally done it, flew it out 1km to a river, lost signal, it turned around and flew back to around 300m and then I took manual control.
All drone flyers should test the failsafe behaviour of their drone to understand what it does and how it does it.
This gives you a lot more confidence so that when you are in a failsafe situation you shouldn't have anything to worry about.
It's not scary at all if you do in a controlled environment.
In a large, open area you fly out about 200 feet, where you can still see it and switch off the controller.
There's nothing to worry about .. you can always turn the controller on and reconnect, but you won't have to because the drone will act just as described in the Failsafe RTH section of the manual.
 
I quite often used to get RTH activated on my mini 1 as soon as I turned for home, the drone seemed to have a real dead spot for transmission in the direction it was pointing.
 
late to the party but ive aaccidentally done it, flew it out 1km to a river, lost signal, it turned around and flew back to around 300m and then I took manual control.
I got a DJI FPV last month, and I end up pushing it to weak or lost signal surprisingly often. The RTH has always worked well.

The control locations are different on the FPV, compared to my Minis, and I haven't fully integrated that yet. On the Minis, the button to start/stop video recording is on the top left of the RC. On the FPV RC, that top left button is the brake/RTH/RTH cancel button. I've been punching the top right button on the FPV control to try to get RTH cancel, but I'm getting used to that being on the left with the FPV.

RTH is a very intelligent and useful feature!

:)
 
I quite often used to get RTH activated on my mini 1 as soon as I turned for home, the drone seemed to have a real dead spot for transmission in the direction it was pointing.
I've seen that too. I notice it most with the Mini-1, but the -2 and the -SE do it too. To a lesser extent the FPV does the same thing.

But when that happens, and it starts to come home, the signal usually restores pretty quickly.
 
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