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Looking for help analyzing Mavic Air crash Data, DJI giving me runaround

Abdinhk

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Hello, I am new to forum. I recently had a crash with a relatively new Mavic Air. It was responding fine and then suddenly it said it was resetting home point while in mid flight. That got me scared as I had lost sight of the drone. I hit return to home and it landed but not where I was, I made it take off again and then it crashed into a building while I was trying to manually fly it back.

I have uploaded the two final flights. You can see that the first one has the home point where I was on the shore, but it shows it landing in what appears to be the water. The tide was out that day so it may have successfully landed on the beach, but that was probably 100 yards from where I was with the controller. The final video shows the home point at the same spot in the water where the first video ends. I never moved from where I was standing in a parking area at least 20 yards from the start of the beach. Here are the two data files

DJI Flight Log Viewer - PhantomHelp.com

DJI Flight Log Viewer - PhantomHelp.com

Have you heard of other instances of the home point resetting on its own. The data shows only the initial home point being set, but then indicates the home point is out in the ocean.

I'd appreciate any help anyone can give me as my experience so far with DJI support has been pretty bad.
 
I don't know about your original home point but the second home point got reset at the spot the second flight took off from.
 
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So,at the end of the first flight, it says Auto Landing, which I assume indicates that I had hit Return to Home, which I had. But it also indicates that it didn't auto land at the original Home Point that set at takeofff, which is where I was standing with the controller.
I remember it saying resetting home point during the first flight and when I hit RTH it landed somewhere else, which must be the point that the second flight set as home point. I never moved from my original takeoff position on land.

So, in your opinion, do these flight logs indicate that the home point did somehow reset on its own during the flight. Is there another explanation of why RTH/Auto Landing would land the drone in a completely different place than the initial home point.

Thanks again,.
 
Can you please describe your take off location and surface?
I'm seeing a whole host of compass errors, so the thing was fighting with its self to even know where it was IMO?
@sar104
 
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The home point in the first flight graphic is correct. It was a parking circle to the left of that zig-zag building and to the right of that space that leads to the building with the blue roof. The parking area is about 10 meters back from the start of the beach. It was probably 120 meters from the start of the zig zag building.

The tide was low that day so much of the beach was dry. The image in the flight log was taken when the tide was high. There were about about 20 to 30 meters of beach before the water started. I flew out over the water, straight out and back to the home point. I sent it out over the water a second time and that's when I got the audio that said something like Setting Home Point. I may have already hit Return to Home at that point. I then waited for the drone, but didn't see it, but then got the message that the drone had landed. I made it take off again and when I was trying to figure out where it was, it crashed into the school building. which you can see at the end of the second flight log.

Again I never moved from the initial Home Point in the parking circle. Thanks for the help.
 
The parking circle was paved. there were a couple of metal street lamps there and a low railing but not much metal that could affect the compass.
 
The second HP is I presume fairly obvious, because yo relaunched, so a new HP would be set.
The issue I believe, is why it went to a position, other than the seemingly recorded HP at initial TO.
Sar104 ?
 
Hello, I am new to forum. I recently had a crash with a relatively new Mavic Air. It was responding fine and then suddenly it said it was resetting home point while in mid flight. That got me scared as I had lost sight of the drone. I hit return to home and it landed but not where I was, I made it take off again and then it crashed into a building while I was trying to manually fly it back.

I have uploaded the two final flights. You can see that the first one has the home point where I was on the shore, but it shows it landing in what appears to be the water. The tide was out that day so it may have successfully landed on the beach, but that was probably 100 yards from where I was with the controller. The final video shows the home point at the same spot in the water where the first video ends. I never moved from where I was standing in a parking area at least 20 yards from the start of the beach. Here are the two data files

DJI Flight Log Viewer - PhantomHelp.com

DJI Flight Log Viewer - PhantomHelp.com

Have you heard of other instances of the home point resetting on its own. The data shows only the initial home point being set, but then indicates the home point is out in the ocean.

I'd appreciate any help anyone can give me as my experience so far with DJI support has been pretty bad.

No mystery here I'm afraid. The flight had numerous problems due to magnetic interference at the takeoff point, which led to all the compass errors, but it was flying under control. The home point was correctly set at 2.2 seconds to 22.38711°N, 114.275868°E. Unfortunately, when you became nervous and wanted to bring it back at 297 seconds, you hit the autoland button instead of the adjacent RTH button, and it immediately entered autoland. It did not give you a message about resetting the home point - the home point was never changed from the original location.

When you took off again the home point was reset, as expected, to the new takeoff location, 22.386178°N, 114.276887°E. The yaw error was still present because it is not reinitialized on motor start, and that likely caused the control issues on the second flight.
 
Thankyou Sensei!

Any time. Just to add - it looks like another concrete/rebar problem at the takeoff site, although the initial yaw error doesn't look to have been very large - the initialized yaw was 82° and the initial flight track was consistent with that heading:

2018-07-29_[17-03-11]_01.png
 
For future reference, if your home point changes mid flight, do not use return to home. I may have overlooked it, but I didn't see where it changed home points mid flight, only the home point change when you landed.

You got a compass warning right at take off. That's something you should have addressed before flying. Your Mavic Air is telling you something isn't right.

You also had a high wind warning followed by several attitude too large warnings. Seems like your Air was fighting the wind. On the second log, you're giving it full stick and only going 6-7mph and flying backwards. Anyone else seeing that or am I reading that wrong?

I"m looking at your stick commands and direction of travel. I could be wrong. My first time analyzing one of these.
 
Sar014, thanks for the message but I don't understand when you say I hit the auto land button instead of return to home.

My controller has a single button on the top left that is a Return to home Button. In the APP. the two options on the screen on the left, are the Auto Takeoff and Return to Home options. I can't be sure whether I tried to bring it home with the controller button or in the App, but I don't see any auto land option that I could have mistakenly hit.

And yes, I did get nervous but I'm sure that was when it the controller said it was resetting the home point.

Thanks
 
For future reference, if your home point changes mid flight, do not use return to home. I may have overlooked it, but I didn't see where it changed home points mid flight, only the home point change when you landed.

You got a compass warning right at take off. That's something you should have addressed before flying. Your Mavic Air is telling you something isn't right.

You also had a high wind warning followed by several attitude too large warnings. Seems like your Air was fighting the wind. On the second log, you're giving it full stick and only going 6-7mph and flying backwards. Anyone else seeing that or am I reading that wrong?

I"m looking at your stick commands and direction of travel. I could be wrong. My first time analyzing one of these.

It didn't reset the homepoint - it was an autoland event. The wind was 10 - 15 mph out of the south, and was not really a factor.

In terms of response, the following graph shows velocity forwards and right relative to elevator and aileron input for the second part of the flight. It is approximately consistent with what you would expect to see.

2018-07-29_[17-10-28]_01.png
 
Sar014, thanks for the message but I don't understand when you say I hit the auto land button instead of return to home.

My controller has a single button on the top left that is a Return to home Button. In the APP. the two options on the screen on the left, are the Auto Takeoff and Return to Home options. I can't be sure whether I tried to bring it home with the controller button or in the App, but I don't see any auto land option that I could have mistakenly hit.

And yes, I did get nervous but I'm sure that was when it the controller said it was resetting the home point.

Thanks

After you take off the auto takeoff button changes to an auto land button.
 
Sar014, thanks for the message but I don't understand when you say I hit the auto land button instead of return to home.

My controller has a single button on the top left that is a Return to home Button. In the APP. the two options on the screen on the left, are the Auto Takeoff and Return to Home options. I can't be sure whether I tried to bring it home with the controller button or in the App, but I don't see any auto land option that I could have mistakenly hit.

And yes, I did get nervous but I'm sure that was when it the controller said it was resetting the home point.

Thanks

And just to reiterate - the aircraft never entered RTH, and the home point was not reset until you took off the second time. The log clearly indicates that autoland was selected.
 
I've been Googling Auto Land and I have many threads of people reporting that their drone auto landed without them initiating the process, with some saying that once it started the process there was no way to abort with the sticks. I'm wondering if that's what happened here.
 
I've been Googling Auto Land and I have many threads of people reporting that their drone auto landed without them initiating the process, with some saying that once it started the process there was no way to abort with the sticks
The drone auto lands when the battery reaches the critically low level. That auto landing cannot be cancelled.

In your case, you accidentally tapped the auto land icon on the left side of DJI GO and then acknowledged the prompt to auto land when DJI GO asked you to confirm your action. That type of auto landing can be cancelled by tapping the RTH button on the remote controller (or from the icon on the left side of DJI GO).
 
I've been Googling Auto Land and I have many threads of people reporting that their drone auto landed without them initiating the process, with some saying that once it started the process there was no way to abort with the sticks. I'm wondering if that's what happened here.

No - you made no effort to abort it with the sticks. You requested autoland at 297 seconds with the autoland button. At 318 seconds you hit the button again, cancelling it and putting it back into P-GPS mode. The at 403 seconds you requested it again, and did not apply any up throttle before it landed. The aircraft behaved entirely correctly throughout.


2018-07-29_[17-03-11]_02.png
 
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I know I am a newbie, but I don't see any autoland button on the controller nor in the APP. This is the screen shot of the button within the DJI Go APP. It does not say autoland, it says Return to Home confirming will bring the drone. I was under the impression that Auto Land kicked in automatically when battery became critically low, which wasn't the case here. Am i missing something?
 

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