Hey everyone,

Was wondering if people with a bit more experience could check out my log and help me understand what happened.

http://www.phantomhelp.com/LogViewer/1EFHY7N3WP87WW7UIMWM/

1. I updated the firmware on my Inspire 2 to the version released in late December, the next day I took it out for a test flight as DJI recommends after updating firmware.
2. I use the same batteries from the night before which were down to about 81% from a full recent charge (i took the batteries from the charger and placed them into the I2 for updating purposes) but I did turn off the drone overnight and left the batteries in not thinking I'd need to recharge them.
3. I take the I2, start it up, do a compass calibration, all connections and signals seemed fine and making sure it was safe to take off with no one around me I set it up in the air.
4. The wind is a little strong where I am, but I literally flew in the same spot underworse conditions tweo days prior so thought nothing of it.
5. The I2 immediately speeds away from me and the RC is unresponsive, could be wind, but again, similar conditions two days prior.
6. I become concerned with it drifting away, I hit RTH....it drifts away a little but more but begins to come back.
7. As it's coming near on top of me, it does not descend and 87.8 seconds in I suddenly get a battery warning and one of the battery fails due to low temperature (it's currently summer in Sydney) and the power goes goes from 70% to 37%.
8. I'm okay, even with the drop the drops is  almost directly above me and it's still in home mode so I wait.
9. Except it's unresponsive and beings to drift again, in RTH mode...
10. I take over manual controls 20 seconds later, nothing, warnings about motor overload (wind?) I couldnt feel too from ground level.
11. My attempt to steer it back manually does not work, I2 continues to be unresponsive and drifting literally out to sea...
12. I watch it go out to sea and my heart is sinking, at 2:45 after take off, I again initialise RTH mode... nothing... I2's trajectory does not change and continues to drift
13. For the next 2:15 minutes i'm trying to get some sort of control, but the I2 continues to be unresponsive and drifts
14. The I2 contineus to drift out to see... my attempts at RTH and manual controls have done nothing, connection still there, I can see the cam, I can see it's got 16 SAT all the way with full bars.
15. The I2 gets to 22% battery, low power mode sets in and RTH kicks in automatically... it drifts another 100 metres out to sea over middle harbour..
16. Then suddenly with no explanation, begins to fly back towards me and the remote.
17. But it has to travel nearly 800 metres on 19% battery...
18. It avoids the water (thank christ) and lands in the middle of a dense bush.

What the hell could have caused it all? Does anyone have any ideas? Did the firmware fail me? because before that update the I2 was just perfect. I can understand that wind would be an issue but it wasn't gail force and I wouldn't have let it up if it wasn't the same conditions it flew in two days previously.

The unresponsiveness was also super scary, not just the RTH mode but also manual flying, it simply did not respond to the remote.

Also feel free to point out what I could have done differently or better, I'm just simply trying to work out what happened.

Thank you in advance

I am sure that was scary.  I do not trust third party data analysis.  It says that the battery cells are perfectly matched.  That does not happen and it lumps two cells together.  I would download the flight data log from the craft and put it on afile sharing site like Google Drive and then post it here for us to analyse.  You can do that through Assistant 2.

Tahoe_Ed Posted at 2018-2-12 06:59
I am sure that was scary.  I do not trust third party data analysis.  It says that the battery cells are perfectly matched.  That does not happen and it lumps two cells together.  I would download the flight data log from the craft and put it on afile sharing site like Google Drive and then post it here for us to analyse.  You can do that through Assistant 2.

Thank you Tahoe_Ed

I hope these are the files you meant?

https://wetransfer.com/downloads ... 180212231927/44fc64

Thanks again,

Did you calibrate the IMU after the firmware update?
Immediate fly-away from takeoff and difficulty in directional control is often a case of a poor set of IMU numbers.

Would suggest you calibrate on a known level surface.

Farnk666 Posted at 2018-2-12 16:16
Did you calibrate the IMU after the firmware update?
Immediate fly-away from takeoff and difficulty in directional control is often a case of a poor set of IMU numbers.

Hi Farnk,

Thank you for your help, I'm pretty sure I did right after I updated the firmware at my house the night before the incident.

I felt like I did everything by the book. Hence my total confusion about what happened. But am totally willing to take the blame and not repeat mistakes if I made critical errors.

Kind Regards,

Touchthesky Posted at 2018-2-12 18:25
Hi Farnk,

Thank you for your help, I'm pretty sure I did right after I updated the firmware at my house the night before the incident.

Not saying you did anything wrong at all Touchthesky - just looking through the series of events as you posted it.

So after the firmware update was done, did you set the Inspire up on level ground and perform the IMU calibration process in the app? I just want to clarify that the IMU and Compass calibrations are different things.

https://forum.dji.com/thread-103007-1-1.html

Would have taken 5-10 minutes.  

Farnk666 Posted at 2018-2-12 20:58
Not saying you did anything wrong at all Touchthesky - just looking through the series of events as you posted it.

So after the firmware update was done, did you set the Inspire up on level ground and perform the IMU calibration process in the app? I just want to clarify that the IMU and Compass calibrations are different things.

Yes, I did it straight after with the USB still plugged into the I2 from my laptop.

It was in landing mode on my living room floor.

I do a compass calibration before every flight as that's recommended by almost advice I've read upon.
Also wasn't implying you were implying anything haha, but more than happy for people to point out missing steps or stuff i overlooked

Touchthesky Posted at 2018-2-12 21:34
Yes, I did it straight after with the USB still plugged into the I2 from my laptop.

It was in landing mode on my living room floor.

Are you sure that was the IMU calibration?  I’ve done that calibration countless time and it was never while plugged into a laptop or a tablet. The IMU calibration is when you have to stand the Inspire on each side, then on its back and then it’s nose.

Blackwood Posted at 2018-2-12 21:42
Are you sure that was the IMU calibration?  I’ve done that calibration countless time and it was never while plugged into a laptop or a tablet. The IMU calibration is when you have to stand the Inspire on each side, then on its back and then it’s nose.

Blackwood, yes.

It was the first time I had done one so I left it plugged in for paranoias sakes.

I also just realised I never did it the first time I activated it. Flew it fine just dandy for a few weeks. Then this latest firmware upgrade and thus my post.

Also could someone share their experiences with the battery? The drone itself feels like could have landed back to where I was had it not been a battery failure.

As I said, I finished charging the TB50s in the early evening, used it to upgrade firmware through my laptop and it was working fine through calibrations. I choose not to recharge it again over night as I thought that may have been detrimental to the battery as I also had two other sets fully charged that evening.

It did report "low temperature" caused one of the batteries to lose it's power... but it was 24 degrees as it's summer in Sydney... albeit 24 is cold for our summer but... 24 degrees...

Not saying it caused your trouble, but doing a compass calibration before each flight is like playing Russian roulette with your drone.

I think you've had a couple of things happen..
Inexperience.
Possibly a Bad compass calibration
Strong winds
Low battery power on one or both batteries
Rc sticks possibly in need of calibration too

I dont see any errors in the logs to show that the control link was disconnected (it would have done RTH earlier if it had), the fact you still had video feed also suggests that you still rc control of the aircraft too. I see a couple of speed errors, and a couple of RTH activations, along with several power errors. I usually see speed or yaw errors in my logs when I've been flying in windy/gusty conditions - a sudden change in speed or direction from a strong gust confuses the IMU and gives an error.

So, I think the following scenario is probably likely with the limited info I've got from your description and logs...

You took off, wind starts drifting the aircraft, you try the sticks but it won't come back because the wind is too strong for it's normal (p_gps) mode. You hit RTH, but again the wind speed overpowers the RTH cruise speed and it carries on drifting. You spend several minutes trying to bring it back against the wind, but thinking it's not responding. During all of this, the high winds mean the aircraft is drawing more power from the batteries and leads to a cell (or more) lowering voltage under load giving errors. The errors add to your sense of loss of control. Eventually the low power RTH kicks in and the aircraft attempts to fly back and makes it far enough to traumatise a poor unsuspecting bush...

Next time you fly in windy conditions be prepared to switch the aircraft to sport mode if it won't fly into the wind, that will allow the I2 to apply more power by increasing its max tilt angle, which will allow it to hit higher speeds. (If a wind speed is over something like 30mph in the normal p-GPs mode, then there's a risk the aircraft can start drifting as it won't compensate enough for the wind speed to hold position.) if it drifts in sport mode, then it's going to go anyway - just land it somewhere quickly, don't just stand and watch it go, and don't rely on RTH it isn't infallible! Lowering your altitude would probably help too as wind speed increases with altitude, so going lower might mean lower winds and less drift... meaning you might be able to fly into it, or at least reduce the rate of drift enough to hover or land somewhere.
If your I2 is still In flying condition, then do another IMU calibration making sure it's on a level surface and that it's done immediately after starting the aircraft up & when it's still cool. After calibration, check the diff values are low and the bar is in the green section of the graph.

Now, find somewhere safely away from anything magnetic, no pipes, no reinforcing, no concrete, no cars etc make sure you've nothing magnetic on your person either, then calibrate the compass.  Walk 20ft or so away after calibration and check the diff values are low and the graph is in the green too. If it's a good cal, then don't recal the compass unless either the I2 asks you to, or you travel 100 or more miles east or west from where you did the compass cal. (North south doesn't have same effect).

Turn off the I2 and calibrate your RC sticks from within the Go4 app - just to make sure they are fully working and giving full power commands.

Finally, if you fly on a partly discharged battery, then be careful. It's usually safe enough, but the batteries aren't going to perform at their best. I often fly down my batteries after they've gone into storage mode at 55-65% charge and don't have problems. Those flights nearly always show the battery voltages dropping rapidly under load (e.g. When climbing), then stabilising when the aircraft is hovering. I always fly very conservatively if the battery isn't freshly charged or above 90%, or if it was used for a flight the day before and left overnight.

I agree a fly away is where you do not recover the craft.  Also you send CVS files, I need the DAT files.  Please download Assistant 2.  https://www.dji.com/inspire-2/info#downloads Connect your I2 and download the flight data logs, DAT only.  We cannot review your flight without them.  Also sync your flight logs to the cloud and pm me you DJI log in ID.

Tahoe_Ed Posted at 2018-2-13 15:59
I agree a fly away is where you do not recover the craft.  Also you send CVS files, I need the DAT files.  Please download Assistant 2.  https://www.dji.com/inspire-2/info#downloads Connect your I2 and download the flight data logs, DAT only.  We cannot review your flight without them.  Also sync your flight logs to the cloud and pm me you DJI log in ID.

Thanks for the reply Tahoe_Ed, I actually included the link in my last reply to you.

Here's a download link at wetransfer

https://wetransfer.com/downloads ... 180212231927/44fc64

It includes the DAT and CVS files you're requesting.

Kind Regards,

Electro-Nick Posted at 2018-2-13 03:50
Not saying it caused your trouble, but doing a compass calibration before each flight is like playing Russian roulette with your drone.

I think you've had a couple of things happen..

Hey Electro-Nick

Doing a compass calibration is what DJI recommends before each flight, it is part of their instructions in the tutorial video for the Inspire 2. Are you saying I should not be doing what DJI recommends in their video? This is super interesting to me as it's now seeming to be there are a lot of conflicting advice between DJI and experienced pilots.

Please note when I did the calibration before the flight I was in the middle of a sports field with no metallic objects nearby as I made sure to follow CASA rules of operating the drone at least 30 metres away from people, cars, etc.

Your depiction of events seem fairly similar to what I experienced, except with an insight of someone with much more experience.

I would say that the non responsiveness was real as my attempts to change the altitude thinking it was the wind was to no avail, again, I didn't feel any strong gusts of wind where I was. But that could have been different where the drone was.

My question would be, why would RTH mode not function untill the lower power mode kicked in? That to me was the weirdest part. The drone behaved consistent in the sense that it drifted away for one reason or another then suddenly corrected itself and attempted to make its way back.

Please note that as soon as the battery dropped I did attempt to land it as the first time it did the RTH. It did not want to lower itself and instead begun the initial drift.

I really appreciate your knowledge and advice but I felt like I did attempt to do what was normal, drone is in trouble, land it immediately, except I wasn't able to then drone just flying about till it suddenly decided not to.

The calibration check you're speaking of I will do, and probably before each flight now just in case.

The catuion about partly discharged battery seems interesting though. It would have been maybe 12 hours between a full charge to me flying the drone, during that time the battery were used for upgrading firmward and imu calibration which took it to the 70s%... I'll be honest and say if the battery can not be operated at that level in decent weather and temperature conditions, I don't really think it's an operators' issue.

I was also surprised as having flown the I2 in Sydney and Hong Kong, I hadn't experienced any issues until I upgraded the firmware.

The biggest irony being I flew in a relatively east spot to test the firmware has being installed correctly, as recommended by DJI.

Thank you again for your time tho, I'm adding a few more details to my pre flight checks that i cut and pasted from DJI

Touchthesky Posted at 2018-2-13 19:37
Hey Electro-Nick

Doing a compass calibration is what DJI recommends before each flight, it is part of their instructions in the tutorial video for the Inspire 2. Are you saying I should not be doing what DJI recommends in their video? This is super interesting to me as it's now seeming to be there are a lot of conflicting advice between DJI and experienced pilots.

Hi, as many have been posting above regarding IMU calibration and respectfully I understand you are not a beginner. But to clarify the procedure and so we are all on the same page, please see the video for IMU calibration.

Also, you are in good hands with Tahoe Ed !!  He will help you get this sorted out
Rich

RichJ53 Posted at 2018-2-13 21:31
Hi, as many have been posting above regarding IMU calibration and respectfully I understand you are not a beginner. But to clarify the procedure and so we are all on the same page, please see the video for IMU calibration.

Also, you are in good hands with Tahoe Ed !!  He will help you get this sorted out

Hi Rich,

I appreciate everyone feeling like they need to step on eggshells but I am totally a beginner and hence the post because I can't really work out what went wrong and what I did wrong and to make sure I don't repeat mistakes

Thanks for the video and yes, that was the procedure I followed.

RichJ53 Posted at 2018-2-13 21:31
Hi, as many have been posting above regarding IMU calibration and respectfully I understand you are not a beginner. But to clarify the procedure and so we are all on the same page, please see the video for IMU calibration.

Also, you are in good hands with Tahoe Ed !!  He will help you get this sorted out

When doing the calibration on the sides, are we to set it on the landing gear to the table, motor to the table or try to hold it level inbetween? The video shows attempting to hold it level for the first side and on the landing gear at an angle on the last side. So what should it be?

Touchthesky Posted at 2018-2-13 19:24
Thanks for the reply Tahoe_Ed, I actually included the link in my last reply to you.

Here's a download link at wetransfer

Thank you Touch.  Did you sync your flight records to the cloud and we will need your log in ID.

Touchthesky Posted at 2018-2-14 03:04
Hi Rich,

I appreciate everyone feeling like they need to step on eggshells but I am totally a beginner and hence the post because I can't really work out what went wrong and what I did wrong and to make sure I don't repeat mistakes  

There are a lot of good people here on the forum.. many experienced veterans trying to help. No one wants to feel being put down after following all the instructions. I just wanted to be sure that we are addressing a problem that was not caused from improper setup procedure.  

Sounds like you did everything correctly, yet this is very odd behavior indeed. I hope that Tahoe Ed can find the possible cause from your logs.

Rich

epicjib Posted at 2018-2-14 05:56
When doing the calibration on the sides, are we to set it on the landing gear to the table, motor to the table or try to hold it level inbetween? The video shows attempting to hold it level for the first side and on the landing gear at an angle on the last side. So what should it be?

IMO it should not matter as long you hold the Inspire very still, no metal and is totally away from radio interference  during the calibration process.  I have held the Inspire straight (on the side) using the case to steady it. I have also let it rest on the antenna legs (slight angle)  no difference for me.

Rich

All I can say is thankfully a fail safe kicked in and saved the day for you. On the Compass Calibration I only do it when the Quad is fresh out of the box (new) and only after that if I receive a banner requiring a Compass Calibration which has only happened once to me and that was when a unit was new.

RichJ53 Posted at 2018-2-13 21:31
Hi, as many have been posting above regarding IMU calibration and respectfully I understand you are not a beginner. But to clarify the procedure and so we are all on the same page, please see the video for IMU calibration.

Also, you are in good hands with Tahoe Ed !!  He will help you get this sorted out

Rich, you got this right from the Motherland

Tahoe_Ed Posted at 2018-2-14 06:06
Thank you Touch.  Did you sync your flight records to the cloud and we will need your log in ID.

Hi Tahoe_Ed,

Should I PM those details to you?

RichJ53: I absolutely agree, the amount of responses I've had is really great and the knowledge and experience is helping me appreciate the community a lot too. Just wanna point out again that because it's hard to read tone on the internet and people get skiddish, I am not at all sensitive to any criticisms if any are leveled at me. I just want a bit of help getting to the bottom of what happened so it doesn't happen again, watch your drone fly over water with barely 20% battery and not responding is not something I'd wish on anyone hahaha.

Rodger8, I am also glad it kicked it, but I just dont understand why it didn't kick in sooner when I asked it to.

Are you also advising to not do compass calibrations before every flight? Again I'm trying to recouncile experienced pilots like yourself's advice against what DJI's official recommendations are. My pre flight checks are basically straight from the DJI tutorial video on the Inspire 2.

Hi Touchthesky,

When I first started flying my P4, I was like you, I did a compass cal at each new site before flight - but after reading up on it and a lot more experience of flying since, I rarely recalibrate the compass on my P4 or I2 now as there's a high risk of unwittingly messing things up!

It might seem like DJI say to do a compass cal before each flight, but I don't think they do. Best thing with compass cals is do it once, get a good calibration result, and leave it until it complains - or until you move far enough east-west from the original site to mean it needs recalibrating again (depending on where you are on the planet,  that can be between 50-100 miles e/w of the calibration site. North-South movement doesn't change the N-S magnetic field alignment enough to warrant recal unless you go a lot further.)

I'm only surmising that there was a stronger wind at altitude as the aircraft was trying to get back to you (it had registered your RTH requests on at least two occasions), but wasn't going anywhere except away from you until the final low battery power RTH kicked in. There are a few yaw errors and speed errors showing in the logs, and they hint at gusty wind from my experience, but may be symptoms of a different problem.

There where various battery errors showing in the logs so it could have been that the I2 was having real problems pulling enough power from the batteries to make any headway. Maybe after it had drifted a bit the offending battery managed to warm up/recover a bit and provide enough juice to get it back to you. GPS satellite count shows as being good throughout, and the home point doesn't vary either, and the fact it did try and return home to you says it could tell the compass directions and get a satellite lock.

Guess we'll just have to hope that DJI can give you some greater insight from their reading of the logs.

BTW, doing the IMU calibration is fine resting on either the motor cans (vertical) or on the antenna legs (at a slight angle)... the main thing is that you do it the same for both sides, and that you can let go and the aircraft remain stable & without much movement - try not to touch or move the aircraft in each phase of the imu calibration. if you have problems balancing the I2 on it's side, then try with the camera gimbal attached - it seems to balance better that way. Basically you're trying to get the best set of steady or baseline set of values for each orientation so it knows how much it deviates from them when flying.

@Touch yes please PM to me.