Drone disconnected and crashed

[slup]

...this almost identical thing happened on an earlier flight, disconnected, started flying sideways but RTH kicked in and saved the day.

Sorry... but can't see any of that in what's available in the DAT log.

Compared your stick commands in pitch & roll with changes in velocity... & all in this flight adds up well (below an example of that comparison).



Also checked the stick commands in pitch & roll vs. the recorded attitude changes... similar there, all adds up well.

When it comes to the disconnect in the end that initiate the RTH... all that can be said there is that everything also adds up before & after the disconnect, no uncommanded attitude or velocity changes at all.

The dark grey area in below chart is the disconnect... nothing can be said about what happens there as the AC wasn't in connection with the RC. The only thing I see that possibly could have been confusing for you is that you tried to fight the RTH sequence (the light blue area) with a full elevator command (right stick forward, dashed purple graph).

Furthermore... the DAT log event stream doesn't show any signs of a battery problem...

So can't see any similarities between this flight & the pervious where you got a battery disconnect.

 

[neco900]

Sorry... but can't see any of that in what's available in the DAT log.

Compared your stick commands in pitch & roll with changes in velocity... & all in this flight adds up well (below an example of that comparison).

View attachment 171205

Also checked the stick commands in pitch & roll vs. the recorded attitude changes... similar there, all adds up well.

When it comes to the disconnect in the end that initiate the RTH... all that can be said there is that everything also adds up before & after the disconnect, no uncommanded attitude or velocity changes at all.

The dark grey area in below chart is the disconnect... nothing can be said about what happens there as the AC wasn't in connection with the RC. The only thing I see that possibly could have been confusing for you is that you tried to fight the RTH sequence (the light blue area) with a full elevator command (right stick forward, dashed purple graph).

Furthermore... the DAT log event stream doesn't show any signs of a battery problem...

So can't see any similarities between this flight & the pervious where you got a battery disconnect.


View attachment 171206

I will try to explain with my limited English,

The problem is(and the drone was actually in my line of sight this time) at 7m25.9 s I was trying to fly towards myself, the drone disconnected and started flying to the right, you can see that part its the red line on the phantomhelper map. I have no idea ehwt the logs show but I'm pretty sure my stick movements wasn't causing that as I was trying to fly towards where the home point was.

 

[slup]

I will try to explain with my limited English,

The problem is(and the drone was actually in my line of sight this time) at 7m25.9 s I was trying to fly towards myself, the drone disconnected and started flying to the right, you can see that part its the red line on the phantomhelper map. I have no idea ehwt the logs show but I'm pretty sure my stick movements wasn't causing that as I was trying to fly towards where the home point was.

Think you don't quite understand how thing's work...

If you have a disconnect between your drone & the RC... your RC commands will not reach the drone & no data from the drone can reach your RC where the log is recorded in the attached screen device.

So a disconnect mainly create an "empty hole" in the log... what you see on Phantom Help is just a straight line, connecting the flight path just before the disconnect, with right after when the connection returns.

So... with the above in mind, you say that you tries to command your drone from 7m 25.9s & that the drone doesn't follow your command. That's not surprising as you there have lost the connection... and the connection returns at 7m 57.9s, and between those 2 time stamps Phantom Help just draws a straight line as it's totally unknown log wise what happens during the disconnect.



So again, this flight have no similarities with the flight where you got a total power loss.

 

[neco900]

Think you don't quite understand how thing's work...

If you have a disconnect between your drone & the RC... your RC commands will not reach the drone & no data from the drone can reach your RC where the log is recorded in the attached screen device.

So a disconnect mainly create an "empty hole" in the log... what you see on Phantom Help is just a straight line, connecting the flight path just before the disconnect, with right after when the connection returns.

So... with the above in mind, you say that you tries to command your drone from 7m 25.9s & that the drone doesn't follow your command. That's not surprising as you there have lost the connection... and the connection returns at 7m 57.9s, and between those 2 time stamps Phantom Help just draws a straight line as it's totally unknown log wise what happens during the disconnect.

View attachment 171207

So again, this flight have no similarities with the flight where you got a total power loss.

Well yeah I don't actually know how any of this works to be honest with you, I figured it wouldn't follow my command but why does it keep flying sideways when its disconnected ? I mean shouldnt it at least stop and hover then RTH? What I was trying to say with my previous post was that it seemed to fly sideways again when it disconnected.

 

[slup]

Well yeah I don't actually know how any of this works to be honest with you, I figured it wouldn't follow my command but why does it keep flying sideways when its disconnected ? I mean shouldnt it at least stop and hover then RTH? What I was trying to say with my previous post was that it seemed to fly sideways again when it disconnected.

As you applies a full aileron command to the right (right stick fully to the right) just when the log stops recording... it's unknown how much longer you applied that command. But as you have 2 connection directions (one up-link & one down-link) it's possible that you first lost the down-link (lost live view & data transfer)... & later lost the up-link which conveyed your stick command for a while, making the drone steer off to the right.

But all of this is speculation as none of it are in the logs.

 

[neco900]

As you applies a full aileron command to the right (right stick fully to the right) just when the log stops recording... it's unknown how much longer you applied that command. But as you have 2 connection directions (one up-link & one down-link) it's possible that you first lost the down-link (lost live view & data transfer)... & later lost the up-link which conveyed your stick command for a while, making the drone steer off to the right.

But all of this is speculation as none of it are in the logs.

View attachment 171208

Ok now I'm starting to understand what is going on I guess, drone seems to keep the trajectory of the last input it receives when it disconnects? I wish there was video footage of this incident at least lol, it behaved like I was trying to crash it into a tree.

By the way another detail I forgot to mention, I was pretty close to a high voltage line, don't really know if that effects anything though.

Anyway I think it's time to upgrade to mavic 3 now, I'll do a couple of test flights with this one and see if it crashes heh, just got a new battery to make sure atleast its not that.

 

[Yorkshire_Pud]

Ok now I'm starting to understand what is going on I guess, drone seems to keep the trajectory of the last input it receives when it disconnects? I wish there was video footage of this incident at least lol, it behaved like I was trying to crash it into a tree.

By the way another detail I forgot to mention, I was pretty close to a high voltage line, don't really know if that effects anything though.

Anyway I think it's time to upgrade to mavic 3 now, I'll do a couple of test flights with this one and see if it crashes heh, just got a new battery to make sure atleast its not that.

Also have a look at the failsafe RTH description in the manual, page 47.
"When Failsafe RTH is activated, the aircraft starts to retrace its original flight route home.
If the remote control signal is re-established within 60 seconds of Failsafe RTH being activated, the aircraft hovers at its present location for 10 seconds and waits for pilot commands.
The user may tap in the DJI GO 4 or press the RTH button on the remote controller to cancel Failsafe RTH and retake control. If no pilot command is given, the aircraft flies to the Home Point in a straight line.
If the remote control signal is still lost 60 seconds after activating Failsafe RTH, the aircraft stops retracing its original flight route and flies to Home Point in a straight line."
Just before the loss of contact you were applying aileron, so the retrace should have started with sideways movement, then gone back along the inbound route. Connection was restablished after 32 seconds with full aileron applied.
There might be a slight lag between joystick input and drone response.

 

[slup]

Also have a look at the failsafe RTH description in the manual, page 47.
"When Failsafe RTH is activated, the aircraft starts to retrace its original flight route home.
If the remote control signal is re-established within 60 seconds of Failsafe RTH being activated, the aircraft hovers at its present location for 10 seconds and waits for pilot commands.
The user may tap in the DJI GO 4 or press the RTH button on the remote controller to cancel Failsafe RTH and retake control. If no pilot command is given, the aircraft flies to the Home Point in a straight line.
If the remote control signal is still lost 60 seconds after activating Failsafe RTH, the aircraft stops retracing its original flight route and flies to Home Point in a straight line."
Just before the loss of contact you were applying aileron, so the retrace should have started with sideways movement, then gone back along the inbound route. Connection was restablished after 32 seconds with full aileron applied.
There might be a slight lag between joystick input and drone response.

All there is correct... unfortunately it's rarely seen in the logs (as it's a disconnect). It's also unknown from where in time the up-link could have disappeared, making it a total disconnect (it's usually from there the failsafe action starts)...

So if the OP continuously applied that right aileron command we see just when the log recording stops, with a working up-link then the drone would have followed a path similar to what's missing in the logs making the drone turn up in that un-logical spot when the total connection is reestablished.

 

[Yorkshire_Pud]

All there is correct... unfortunately it's rarely never seen in the logs (

but really my post was aimed at probably explaining some of the sideways flight that @neco900 saw when the drone disconnected near enough above him.

 

[EricJT]

The Mavic 2 series is infamous for ejecting the battery on the slightest swelling... both due to that a swelling haven't any free space between the drone & battery to grow in before starting to being pushed out (like the Mavic Pro 1)... & that the battery latches are really poor. We have seen numerous of cases here at the forum.

And that the battery is flat cold doesn't mean that it doesn't swell up when hot...

Or you maybe didn't clip the battery in place properly..?

That is precisely why I put a velcro loop strap around the M2P /battery to avoid a battery ejection issue. I got that idea on one of these forums.

 

[Meta4]

Ok now I'm starting to understand what is going on I guess, drone seems to keep the trajectory of the last input it receives when it disconnects?

No ... if there is a full disconnection and all signal is lost, the drone will have no signal input, stop and RTH.
But if you only have a partial loss of signal and still have the uplink intact, uou still have control of the drone even though you won't get feedback from it.

By the way another detail I forgot to mention, I was pretty close to a high voltage line, don't really know if that effects anything though.

It doesn't have any effect.