Took off with 14-16 sats, P mode - hovered for a few secs to confirm all was well, ascended to about 50M, started flying north in a large sweeping arc towards the east came back toward the home point, hovered a bit and suddenly the I2 lost GPS with no warning and started doing weird horizontal loops and then flew in a straight line almost due north - I was able to gain control until GPS came back - flew home and landed very carefully - very scary.  How you go from 19 sats to no GPS is beyond my understanding - If I wasn't at 50M it would have been straight into the trees.... be forewarned - kinks not yet worked out....
-john

sounds like you lost your compass calibration. the I2 also relies on the compass and your elliptical turns looks more like that than GPS

  

Did you happen to get in contact with the Support team to have those flight records analyzed?

DJI-Jamie Posted at 2017-2-15 22:14
Did you happen to get in contact with the Support team to have those flight records analyzed?

When i had my issue i checked the flight records using the analyser built into the assistant 2. (its not fully translated from Chinese but fortunately in speak Mandarin)

It showed that GPS sats was consistent number during the whole flight but the compass was flicking around unable to find "north" for a short time. As the I2 relies on both compass and GPS for P mode the next day did a compass calibration and not had any issues since.

In the case mentioned here in this thread I would have switched to ATTI to get control back as GPS and other aids are not active in this mode and brought it back in this mode.   

I also advise to update to the latest DJO GO 4 as I noticed there are some changes associated with the compass calibration accuracy (on the same page as IMU information)

Dr Jon Posted at 2017-2-16 00:20
When i had my issue i checked the flight records using the analyser built into the assistant 2. (its not fully translated from Chinese but fortunately in speak Mandarin)

It showed that GPS sats was consistent number during the whole flight but the compass was flicking around unable to find "north" for a short time. As the I2 relies on both compass and GPS for P mode the next day did a compass calibration and not had any issues since.

Yes - didn't think of that - the strange behavior took me by surprise and all neurons were on regaining control at a safe altitude.

I have the flight record and you can see the warning come up as the problem occurs "GPS Signal Lost" - the location actually skips to the point far north and then the drone makes a B-line to that point.

I have not been prompted to calibrate the compass - I did it once on delivery for my location - so following DJI instructions in that regard.

I will upload the flight record to DJI if someone tells me how to do that....

-john

connect your I2 to assistant 2 then go to flight records in the options list on the left hand side. Choose the flight data for the flight you had issues (date/time)

you can select to download to a location on your computer. The best place to store to send to DJI is a dropbox is you have one then copy the link and post it on this link so Jamie can forward to DJI

OR even better still raise a support request on the support site and then send the file to them once done.

Be warned DJI never tell you if there is anything serious. Most likely they will say calibrate IMU or compass. or....

ocelot27 Posted at 2017-2-16 03:02
Yes - didn't think of that - the strange behavior took me by surprise and all neurons were on regaining control at a safe altitude.

I have the flight record and you can see the warning come up as the problem occurs "GPS Signal Lost" - the location actually skips to the point far north and then the drone makes a B-line to that point.

I calibrate my compass every new location I fly if possible, it is reccomended.... some think it is overkill, but it gives me piece of mind to take that out of the equation should the inevitable/regretteable happen. Keep in mind that concrete/man made surfaces often have conduit or rebar in it,  which makes them unsuitable for calibration....natural open spaces are best.

I also recalibrate my imu regularly after firmware upgrade, airline travel, extended car travel or bumpy long hike.  At home its easy I know my table is level.  On location, especially after travelling by airplane, I break out the bubble levels and have at it.  I prefer not to use the level on the iphone because it has its own calibration needs, and may be off to begin with.  Bubble levels are cheap, use 2,  it allows you to make sure a surface is not convex or concave.

Properly calibrated compass and Imu prevents a whole host of issues: drift, toilet bowl, gimbal roll error, long imu warmups, etc..etc...

thomasakira Posted at 2017-2-16 05:16
I calibrate my compass every new location I fly if possible, it is reccomended.... some think it is overkill, but it gives me piece of mind to take that out of the equation should the inevitable/regretteable happen. Keep in mind that concrete/man made surfaces often have conduit or rebar in it,  which makes them unsuitable for calibration....natural open spaces are best.

I also recalibrate my imu regularly after firmware upgrade, airline travel, extended car travel or bumpy long hike.  At home its easy I know my table is level.  On location, especially after travelling by airplane, I break out the bubble levels and have at it.  I prefer not to use the level on the iphone because it has its own calibration needs, and may be off to begin with.  Bubble levels are cheap, use 2,  it allows you to make sure a surface is not convex or concave.

Does it prevent total loss of GPS signal without any warning?  This isn't my first trip to the rodeo - been flying the Inspire 1 for over a year and RC helicopters since the late 80s.

I'm just wondering if you don't have a lose connector or lose connection some where in the GPS or flight controller circuit?  Another possibility is some thing external to the I2 causing or jamming the GPS signal in your flight area.  Probably not likely but a thought.

ocelot27 Posted at 2017-2-16 08:35
Does it prevent total loss of GPS signal without any warning?  This isn't my first trip to the rodeo - been flying the Inspire 1 for over a year and RC helicopters since the late 80s.

giddy-up cowboy

Dr Jon Posted at 2017-2-16 00:20
When i had my issue i checked the flight records using the analyser built into the assistant 2. (its not fully translated from Chinese but fortunately in speak Mandarin)

It showed that GPS sats was consistent number during the whole flight but the compass was flicking around unable to find "north" for a short time. As the I2 relies on both compass and GPS for P mode the next day did a compass calibration and not had any issues since.

Hello Dr Jon,

I'm surprised that you get some readings from the flight records on the Assistant app. I tried but had just a blank screen. When i connected the I2 to the assistant to see the flight logs (after my last problems with the sluggish yaw movement of my AC) i had two messages shown on the screen:

1. Downloading "Data"
2. Decoding "Data"
3. Blank screen

I'm running the Assistant app 2 V1.0.9

My first impression was that the Assistant App could not handle the Data and that we have to wait for a new update...

Patrick

I agree with Dr. Jon. The flight pattern (TBE, elliptical path) suggests a compass problem.

However, that usually results in an appropriate error message. And compass calibration issues usually result in fight irregularities at the beginning, not the end of the flight. Possibilities
1. GPS jammer active
2. Connection loose in craft (unlikely but easy to check)
3. Major source of magnetic interference near your HP.

John, we're concerned much about your feedback and would like to help you analyze the flight records and data as soon as possible.
Just to clarify, your APP account is the same e-mail address used for forum here? if no, please provide me your APP account username (e-mail address) since you've synced your flight records through DJI GO.
Then please connect your aircraft to a PC with assistant 2 installed and export the flight data as well, you can upload it to dropbox, I'll transfer the data to our engineers for analysis once I get it from you.
Thank you for your support again!

DJI Natalia Posted at 2017-2-16 19:04
John, we're concerned much about your feedback and would like to help you analyze the flight records and data as soon as possible.
Just to clarify, your APP account is the same e-mail address used for forum here? if no, please provide me your APP account username (e-mail address) since you've synced your flight records through DJI GO.
Then please connect your aircraft to a PC with assistant 2 installed and export the flight data as well, you can upload it to dropbox, I'll transfer the data to our engineers for analysis once I get it from you.

yes that's correct - I have downloaded the flight records but don't use dropbox - i can email the file anywhere if you PM me...

Mike-the-cat Posted at 2017-2-16 16:10
I agree with Dr. Jon. The flight pattern (TBE, elliptical path) suggests a compass problem.

However, that usually results in an appropriate error message. And compass calibration issues usually result in fight irregularities at the beginning, not the end of the flight. Possibilities

That's all good - but when the manual says to calibrate the compass only when prompted and this has also been the recommendation of many armchair quarterbacks here and on the Mavic forum - that's what I do.  

Again - no compass calibration prompt - the compass was calibrated at this exact site - no 'rebar" or neodymium magnets glued all over the aircraft - just good 'ol earth and my clothed body sans controller, cell phone keys etc.  This calibration was done for the current firmware.  I check the compass and IMU status before every flight.  I waited for as many sats as would connect (14-16) then took off as usual.  Suddenly the app flashed "GPS signal lost" and all hell broke lose.  Luckily there were no people around - if the aircraft was hovering at head height someone could have been seriously injured - and I would be held liable - that's the issue.

-john

Losing gps and automatically being in atti mode flight is one thing. Losing gps and the bird flying on its own with no pilot stick control control is quite another, serious issue- if I'm reading the situation correctly. I had a compass error with my phantom once but it automatically started flying with atti mode behavior and I still had control at least. There was a red compass error message as well. I'll be interested to hear what the outcome is with your situation. Personally, I wouldn't fly that bird until it's figured out.

Had the same identical problem, during most of my first flights in different days and different locations. Total loss of GPS, erratic flight patterns, etc. I did an IMU reset and a full calibration and it has been working fine since then. I also noticed, during the process, that despite my firmware was up to date, the Assistant 2 app prompted me to update (Red button), so I also updated the bird.

The only issue after that was the BIGGEST scare I ever got, I manually selected a channel (2.4 / 20) and flew in roughly 1.3 km away in the middle of a lake. All of a sudden, without much warning I lost signal, the DJI GO app went blank and NEVER recovered the signal. After waiting for the I2 to return home for a few minutes, I got really alarmed, then I went into a full panic (I have insurance, but in the middle of a lake...), then I tried to push RTH, still without any signal on screen. I also exited the app, still no sign of like, but after a few more minuted I saw the I2 over me, starting to descent. I then manually tested the sticks and I realized I had some control, so I landed it manually, but I never regained app control. To do that, I had to reboot. When I look at the flight logs on screen, tracing stops where I lost signal and nothing else is listed.

I guess I could download the logs via Assistant2. Anyway, I attributed the loss to the manual signal. Scary, scary moment. I lost signal on my drones (p4, P4pro, Mavic, Inspire1) a million times before, but I always regained it eventually, this time it was really freaky.

Elektrica Posted at 2017-2-17 13:29
Had the same identical problem, during most of my first flights in different days and different locations. Total loss of GPS, erratic flight patterns, etc. I did an IMU reset and a full calibration and it has been working fine since then. I also noticed, during the process, that despite my firmware was up to date, the Assistant 2 app prompted me to update (Red button), so I also updated the bird.

The only issue after that was the BIGGEST scare I ever got, I manually selected a channel (2.4 / 20) and flew in roughly 1.3 km away in the middle of a lake. All of a sudden, without much warning I lost signal, the DJI GO app went blank and NEVER recovered the signal. After waiting for the I2 to return home for a few minutes, I got really alarmed, then I went into a full panic (I have insurance, but in the middle of a lake...), then I tried to push RTH, still without any signal on screen. I also exited the app, still no sign of like, but after a few more minuted I saw the I2 over me, starting to descent. I then manually tested the sticks and I realized I had some control, so I landed it manually, but I never regained app control. To do that, I had to reboot. When I look at the flight logs on screen, tracing stops where I lost signal and nothing else is listed.

I've looked through the log very carefully and the strange looping behavior happened just before I got the "GPS Signal Lost" warning on the app - I had 19 sats at that time.  Then it's like the bird thought it should be 150m due north and made a b-line to that point at full speed but there is no recording of that in the log - but there is video!!!

I really wish someone from DJI would chime in and tell me what to do.  I recalibrated the IMU and compass yesterday and did a short test flight and all seemed normal.

The scary thing is the craft just took off at full speed and in a perfectly straight line until I regained control - what if this were at a wedding, sporting event, etc etc etc - DJI should really take this stuff more seriously or they're going to intimately learn the ins and outs of the American tort system.

-john

Sometimes these issues are truly an isolated one-off. Keep flying modestly for a bit and see how it's going. I usually fly a new bird very close in for quite a while during testing and confidence building in the crafts behavior. After a while when I'm confident the bird is a good one, I let the leash out more and more. Short of an answer from dji, that's the best way to regain confidence.

ocelot27 Posted at 2017-2-17 09:35
yes that's correct - I have downloaded the flight records but don't use dropbox - i can email the file anywhere if you PM me...

In that case, please send an e-mail to support@dji.com with the flight data, then tell me your ticket number so that we can follow up it.

Thanks for posting this! How did it handle when you lost gps? Was it the old school drone feel or simple out of control?

sad story... ntg can be done if this happen