Yayyyyy it's my turn, gather round everyone!

I decided to go for a quick flight after church, I got some good photo's and some cool video but was setting up to do a manual quick shot when things turned ugly. I was positioning myself to the side of the flagpole but from the video it looks like I deviated back to the center, upon hitting the flag pole the Mini lost all control and took off full tilt for the highway. It crossed the highway and entered Dollar General's parking lot and it seemed like I regained control but I was in panic mode trying to prevent it from hitting anyone, the mini crashed into the buildings sign and flew inside the Dollar General and Thankfully crashed behind the shopping carts. The video signal cut off after it flew inside and I took off and hurried over preparing for the worst thinking it flew into somebody. I walked in with my controller asking if anyone seen a drone fly in and the Cashier pointed to where it crashed. Outside of major embarrassment and some laughing spectators I'm incredibly thankful that it didn't hit anyone and I can laugh about it now after the fact.

Here's the video and the flight logs, I really can't tell why it took off after crashing so if someone want's to dig into that one. Air data showed an error that the compass was freaking out around the flag pole so magnetic interference was a contributing factor but I'm unsure if that's the whole story.



Air Data Log Phantom Help Log

I've seen videos of the Mini acting like this where it takes off full tilt and eventually leveling out and it looked like mine was on the same route if I had the space, I was too busy trying to correct it's flight and even tried RTH with no response until right before crashing.

WOW - you are such a lucky boy - you had sooooo many near misses in that one flight - I suggest you buy a lottery ticket ASAP with that sort of luck

Pleased it all worked out OK

Hi,

Wow, indeed so lucky that your MM did not hurt any people!

Interesting case this is.

From start of your flight up to 14m7s all looked normal, well i do no see any error and compass values looks oke to me.

But hovering in front of a building at low height (1.6 meters) had effect on the compass?!.
See data in my chart where you can see that the compass data and a yaw reference value divert from each other.

Beacuse of this MM started to fly away (red move line). Weird is that the 2 values did join again, mayby this explain why at the end MM did hover for a very short moment jus before flying into that building.

So what is the cause ?  did your MM picked some interference at startup and after 14 minutes act on this?  Or did it picked up some interference flying low in front of that building? Or did hitting the flagpole (metal one?)  did something to the compass?
Or another cause wich i do not see?
Interesting to read what other forum readers thinks what is the cause of this fly away.

cheers
JJB

It did aerobatics w/o issue.  DJI needs to make a freestyle drone.  0:15-0:16 was some awesome freestyle.

Spectacular flight..
Happy no one got hurt..

Mini was looking for a bag of tortilla chips and jalapeno cheese dip.

JJB* Posted at 2-24 03:46
Hi,

Wow, indeed so lucky that your MM did not hurt any people!

I wouldn’t rule out picking up interference from the ground as it’s not the compass that’s effected when craft leaves the ground it’s IMU that’s out of kilter, so compass gets interference on the ground and when it leaves the interference it corrects its heading but leaving IMU out of kilter, I’ll explain below, the problem is how it lasted so long in the air without any real glitches and did flying to close to possible interference cause all hell to break loose, also we have come to know from similar experience that when compass has a problem dji craft will ditch gps in favor of compass but in your case I see towards end of flight RTH which doesn’t Normally work without gps.

You don’t mention checking compass before take off and looking at location you took off from possibility of interference was high, so hard to rule out interference on the ground.

If this was the case I have seen already two different people get warranty, no explanations just new drone, so report incident to dji support and see how they see it.

Labroids seems to be able to get deep down in the dirt on these cases so maybe he will spot something else here.


The best way I can explain this is. If you put your Aircraft on the ground in normal circumstances, start it up, then lift it up and turn it 90 degrees to the right both your compass heading and IMU will both move together 90 degrees and no problems.
If you put your Aircraft on the ground and there is magnetic interference only the heading of your compass will change, your aircraft will still take off. But when it clears magnetic interference compass will then move to correct heading which you would think was great. But No, what happens is IMU is then conflicted and confused because of this sudden movement by compass, so you receive IMU exceptional heading warning, your aircraft cannot deal with data conflict so decides to switch to Atti mode dropping gps in favour of compass simply because aircraft can fly without gps but not compass.

While I can’t be certain you picked up interference from the ground or surrounding area it is the most common cause.
I have seen many cases where people start their aircraft in or on their car in their house and then bring it outside so damage is already done and we will see exact same warnings and and reaction from aircraft.

We all should check our compass when we start our aircraft and maybe more of this could be avoided, you can do this by checking the small red triangle in the lower left corner of your telemetry.

The church needs to add a "No open carry of drones" sign, lol.

hallmark007 Posted at 2-24 05:52
I wouldn’t rule out picking up interference from the ground as it’s not the compass that’s effected when craft leaves the ground it’s IMU that’s out of kilter, so compass gets interference on the ground and when it leaves the interference it corrects its heading but leaving IMU out of kilter, I’ll explain below, the problem is how it lasted so long in the air without any real glitches and did flying to close to possible interference cause all hell to break loose, also we have come to know from similar experience that when compass has a problem dji craft will ditch gps in favor of compass but in your case I see towards end of flight RTH which doesn’t Normally work without gps.

You don’t mention checking compass before take off and looking at location you took off from possibility of interference was high, so hard to rule out interference on the ground.

Hiya,

Good text Hallmark. As you can see in this log the compass data dit not change after take-off.
If this would be the case than there is a difference in actual heading and the indicated heading.
What we see in compass/way errors that not always after take off compass data changes, but somewhere later in flight.I never saw in DAT files the yaw reference value changing, does look like its always the compass hdg data to change.
I am not sure if an interference picked up at the ground can be 'silent' for 14 minutes and than suddenly appear.
In this flight before the fly away a lot of yawing and heading changes, imo this would show a yaw error, out of sync of yaw signals, earlier.

BTW ; I always mention to check before takeoff to check compass hdg on the ground, on my checklist as well on some videos i posted here.

So mayby the problem is in the IMU and not the compass, but how do an IMU gets its start reference value regarding heading changes??
Not from IMU calibration, and not from acc meter and not from gyro in that channel. They measure only the amount for heading changes (plus direction) and rate of change.
At powering up the IMU record/get a yaw heading ref value wich is compared during flight with the heading info from the compass. With manual or sw yaw input the ref signal is updated. In normal situation if actaul yaw is disturbed, the out of sync value is used by sw to steer back.
Both signals can be out of sync (on MM more than for Spark/MM) but as long as both signals are changed in the same amount and direction : not a problem.
If they out sync than yaw error messages and if too much a fly away.

So did the 'crash' with the flagpole changed the compass value or the IMU ref value? But mayby others can explain better.

Minor thing ; checking the red triangle on a MM does not work, its not there. You have to open the map view and check the blue triangle.

Yaw values for the whole flight.

cheers
JJB

JJB* Posted at 2-24 06:29
Hiya,

Good text Hallmark. As you can see in this log the compass data dit not change after take-off.

There is no set time we see interference kick in on these drones, some in minutes some in seconds, I don’t know and it’s not clear in logs, it could be interference is slight so we don’t see as early in flight as against large interference where we see immediate problems and very fast fly away by drone, could his problem be exacerbated when he crashed into pole , was crash into pole result of heading being off I don’t know and I’m sure more will show in .dat files.

It is also unusual that when IMU heading is off and compass problem that gps is still intact resulting in this case of a Rth , also PH logs don’t show yaw warnings , maybe SW issue.

Magnetometers are used to determine heading of craft, and help with orientation drift.

Nice to see change in colour of triangle in fly app, just as well there is only 1 triangle, will save any confusion .

this is not ok.  regardless the technical explanation.  

The Saint Posted at 2-24 08:21
this is not ok.  regardless the technical explanation.

Your right it’s not ok. If you do no checks before flying and proceed to fly around potential hazards for a drone, no to mention close to peoples property and of course people, environment is extremely important when deciding where and how you intend to fly, and it’s quite possible if some considerations where thought out before flying, then this crash may have been averted.

Nice photo by the way!
It almost seems like the MM did a 180 flip... He got freaked out!
It also went soooo close to all those wires... lucky nobody got hit...
Is the Drone very damaged?

Hello and good day ABeardedItalian. I am sorry to read and to know what happened to your previous flight with your DJI Mavic Mini. This is not the experience we want you to have with DJI and with your DJI Mavic Mini. Since there was a crash that happened and if you feel that the said drone is on performing or functioning well on your next flights. I would recommend you contact our DJI support team at https://www.dji.com/support?site=brandsite&from=nav for us to be able to check and analyze the said drone further. Again I am sorry for the trouble and have a safe flight always. Thank you.

What should I say... it's amazing(ly) scary how awry things can turn... I noticed in the logs values didn't seem to add up anymore after the first impact.

I was wondering @JJB I like your program... I don't remember where have I got it from, I suppose it was the only one available for download, but what screen res. is it made for ?

I have 1920x1080 panel but the prog. window is maxed out, the bottom part is out of my view. Tried messing with .ini (If I recall correct) and didn't seem to change anything, wondering if it's in the registry. Any help appreciated.
Anyway thanks for the entertaining video and correlated data files ABI... how's the Mini?

hallmark007 Posted at 2-24 08:28
Your right it’s not ok. If you do no checks before flying and proceed to fly around potential hazards for a drone, no to mention close to peoples property and of course people, environment is extremely important when deciding where and how you intend to fly, and it’s quite possible if some considerations where thought out before flying, then this crash may have been averted.

I take full responsibility for not doing a full flight check, call it trust or call it ignorance but I've never had a problem with my mini outside firmware behavior. Some flights I'll do a full check but everything was normal, I waited for gps, rotated my controller, my headings were correct and my home point was set. I took off and all my inputs responded just as they always have.

I proceeded to fly for 14 minutes and I had full control over it during that time. I was in full control as I crashed into the flag pole but once it hit the pole it acted on it's own. I've had one prior crash with the mini flying into my porch door trying to land and it just dropped then, I'm really surprised it took off instead of just crashing.

This leads me to my original questions as to why the drone took off instead of just "crashing" and falling.

I had permission to fly here and it was only when when I was the last one here that I flew close to the building, while being close to power lines was non optimal conditions I had no adverse effects from flying here previously. I was staying away from the highway at all costs and flying within the rectangle area so to speak.

DJI Stephen Posted at 2-24 08:48
Hello and good day ABeardedItalian. I am sorry to read and to know what happened to your previous flight with your DJI Mavic Mini. This is not the experience we want you to have with DJI and with your DJI Mavic Mini. Since there was a crash that happened and if you feel that the said drone is on performing or functioning well on your next flights. I would recommend you contact our DJI support team at https://www.dji.com/support?site=brandsite&from=nav for us to be able to check and analyze the said drone further. Again I am sorry for the trouble and have a safe flight always. Thank you.

Thanks Stephen, I broke a thumb stick during the ordeal and haven't tried flying since.

Only some scuffs to the underside and my props a bit more beat up, no visual damage was found, when my controller got into range I noticed I still had video so I believe the gimbal survived.

I'll post back when I get a chance to fully evaluate the damages.

Thank you.

ABeardedItalian Posted at 2-24 09:06
I take full responsibility for not doing a full flight check, call it trust or call it ignorance but I've never had a problem with my mini outside firmware behavior. Some flights I'll do a full check but everything was normal, I waited for gps, rotated my controller, my headings were correct and my home point was set. I took off and all my inputs responded just as they always have.

I proceeded to fly for 14 minutes and I had full control over it during that time. I was in full control as I crashed into the flag pole but once it hit the pole it acted on it's own. I've had one prior crash with the mini flying into my porch door trying to land and it just dropped then, I'm really surprised it took off instead of just crashing.

Thank you for reply, first I wasn’t referring to heading from radar, but compass heading which is not the same thing but is the most important thing to check, I had mentioned about picking up interference on the ground for two reasons, 1/ it seems if interference is picked up from ground dji are accepting responsibility, for whatever reason I’m not sure, 2/ picking up interference on the ground it by far the most common place to have this happen, picking up interference in the air is extremely rare and it’s not certain from device log this is what occurred , usually crashing will cause a couple of things 1/ props broken combined with movements from controller could cause strange movements ( but I don’t think this was the case) 2/ warning message motors obstructed which we never seen, it’s very rare to see a crash cause compass problem like we seen here, but compass could have been interfered with by flying close to metal objects which is quite possible . I think log from .dat file may show more of what happened.


Natural and Artificial Magnetic Anomalies Warning
Note
The following information has not been objectively tested to determine it’s impact on a Drones compass accuracy in flight.
        1        Many things can distort the earth’s magnetic field in the area you are flying:
        •        Steel framed or reinforced concrete buildings, bridges and roadways, iron pipes and culverts, high power electric lines, heavy equipment, trucks and automobiles, steel tanks, electric motors and even computers.
        •        Flying between steel framed or reinforced high rise buildings will distort the magnetic field in addition to causing GPS multi-pathing.
        2        Safe distances for compass calibration
        •        6” (15 cm) minimum: Metal rim glasses, pen/pencil, metal watch band, pocket knife, metal zipper/buttons, belt buckle, batteries, binoculars, cell phone, keys, camera, camcorder, survey nails, metal tape measure.
        •        18” (50 cm) minimum: Clipboard, data collector, computer, GPS antenna, 2-way radio, hand gun, hatchet, cell phone case with magnetic closure.
        •        6 ft (2 m) minimum: Bicycle, fire hydrant, road signs, sewer cap or drain, steel pole, ATV, guy wire, magnets, chain-link fence, bar-wire fence, data collectors
that use a magnet to hold the stylus.
        •        15 ft (5 m) minimum: Electrical box, small car/truck, powerline, building with concrete & steel.
        •        30 ft (10 m) minimum: Large truck, metal building, heavy machinery.
Not from wiki, but drone flight school.

hallmark007 Posted at 2-24 08:06
There is no set time we see interference kick in on these drones, some in minutes some in seconds, I don’t know and it’s not clear in logs, it could be interference is slight so we don’t see as early in flight as against large interference where we see immediate problems and very fast fly away by drone, could his problem be exacerbated when he crashed into pole , was crash into pole result of heading being off I don’t know and I’m sure more will show in .dat files.

It is also unusual that when IMU heading is off and compass problem that gps is still intact resulting in this case of a Rth , also PH logs don’t show yaw warnings , maybe SW issue.

If magnetometers determine the heading of a craft, why do we need a compass?
AFAIK magn meters determine the yaw heading variations, this from a reference value wich is inititiated at IMU start up.  I always thought that this ref signal is obtained from the compass.

I see lot of compass / yaw / imu errors where the craft doesn`t go into ATTI mode due to not using GPS data. And not always errors in the logs. As in this flight.

Checking compass heading before take-off just eliminates just one type of a fly-away.
Just saw an example of this, MM on the ground facing South but compass did indicate 055.
So after take-off the SW wants to hold its GPS position, but ofcourse the steering input is set to the wrong blades, as SW think that the heading is 055 and not South. Typical example of fly away right after start.

In this flight the aircraft movement and heading were the same first 14 minutes, so what happend to wich electronic part at what time....  ;-)

cheers
JJB

m80116 Posted at 2-24 08:50
What should I say... it's amazing(ly) scary how awry things can turn... I noticed in the logs values didn't seem to add up anymore after the first impact.

I was wondering @JJB I like your program... I don't remember where have I got it from, I suppose it was the only one available for download, but what screen res. is it made for ?

Hiya,

Last version FRAP is made now for lower res screens as well.

Do you ask how my Mini is? My MM is OKE, no errors etc So realy pleased with my MM.
FRAP does not change anything to windows registry, all what is needed is in the exe file compiled.
cheers
JJB

JJB* Posted at 2-24 11:10
If magnetometers determine the heading of a craft, why do we need a compass?
AFAIK magn meters determine the lef or yaw heading variations, this from a reference value wich is inititiated at IMU start up.  I always thought that this ref signal is obtained from the compass.

IMU on drones and I’m sure it’s the same with dji drones include a magnetometer, mostly to assist calibration against orientation drift.

Can’t answer question because I don’t know what “ lef” is. Also your GPS “fly away” or whatever you’re calling it , maybe point to link so we can see what your seeing.

And your last question is something I have already said is better looking in .dat file for the answer as no one here so far seems to know .

Thank You so much @JJB, I updated it.

How's the Mini was for @ABeardedItalian

ABeardedItalian Posted at 2-24 09:09
Thanks Stephen, I broke a thumb stick during the ordeal and haven't tried flying since.

Only some scuffs to the underside and my props a bit more beat up, no visual damage was found, when my controller got into range I noticed I still had video so I believe the gimbal survived.

Where was the Mini when you started it up and took off?

Geebax Posted at 2-24 15:01
Where was the Mini when you started it up and took off?

From the parking lot one space over from my truck, if what hallmark has posted is correct then I took off to close to my vehicle. I only start the drone when it's in take off position as I've had IMU errors from carrying it while it's powered.  

So far it doesn't look to good, I didn't get a chance to test for very long yesterday but doing the flight check I found none of my camera buttons worked on the remote and only using my phone to start/stop video worked. I couldn't change flight modes and it even said N/A at one point, I landed and restarted and still couldn't change flight modes or use the camera functions on my remote.

I'm going to try with a different battery and having the remote fully charged to see if that makes any difference, maybe even try flashing the firmware again but so far It's not functioning like it should.

I have care refresh and if need be I'll open a ticket with support but crossing my fingers it's not fully broken.

hallmark007 Posted at 2-24 11:31
IMU on drones and I’m sure it’s the same with dji drones include a magnetometer, mostly to assist calibration against orientation drift.

Can’t answer question because I don’t know what “ lef” is. Also your GPS “fly away” or whatever you’re calling it , maybe point to link so we can see what your seeing.

Got a link for how to pull the .dat? I remember seeing it in another users post but couldn't find it again.

ABeardedItalian Posted at 2-25 07:32
Got a link for how to pull the .dat? I remember seeing it in another users post but couldn't find it again.

Hi,

DAT file on your mobile device ; Root /  DJI go 5 / Flightrecord / MCDatFlightRecords.

Look for FLY062.DAT.

cheers
JJB

THAT is an awesome video! I mean I don't want to try and replicate it myself, but wow.

Glad things worked out ok.

Cheers!
=C=

ABeardedItalian Posted at 2-24 09:09
Thanks Stephen, I broke a thumb stick during the ordeal and haven't tried flying since.

Only some scuffs to the underside and my props a bit more beat up, no visual damage was found, when my controller got into range I noticed I still had video so I believe the gimbal survived.

You are very much welcome ABeardedItalian. Please keep us posted and if you have any other concerns or inquiries with DJI. Please feel free to post it here at DJI Forum. We are all here to help and support you. Thank you.

Wow that was crazy video. You were very lucky indeed. Hopefully you get it sorted out.

JJB* Posted at 2-25 07:45
Hi,

DAT file on your mobile device ; Root /  DJI go 5 / Flightrecord / MCDatFlightRecords.

Unfortunately my Auto sync was still enabled and the .dat is already gone, I only have the one from my second flight the next day where my camera buttons were not responding.

To windy and wet out to try again today.

ABeardedItalian Posted at 2-25 11:13
Unfortunately my Auto sync was still enabled and the .dat is already gone, I only have the one from my second flight the next day where my camera buttons were not responding.

To windy and wet out to try again today.

bad luck, my habit since having a MM is to download log and dat before syncing.

Update.

I got a chance to try it again today and I'm happy to report all seems well, I've had the no flight mode happen to me before and I think it's caused when the remote is less then 70% power. All buttons respond, the logs look healthy to me, no erratic hover in sport mode, all modes available,

Note: Only change from my last post was charging the controller.

Air Data Log Phantom Log Dat File

Looks like I just need to order another set of sticks and I'll be back in action, I had a set of aluminum tineer ones but I managed to break them but it's nice to see they were actually metal although cheap..

ABeardedItalian Posted at 2-26 12:00
Update.

I got a chance to try it again today and I'm happy to report all seems well, I've had the no flight mode happen to me before and I think it's caused when the remote is less then 70% power. All buttons respond, the logs look healthy to me, no erratic hover in sport mode, all modes available,

Good news!  and not a single error in the log!

Happy many landings,

cheers
JJB

Wow, through the front door of the store and everything. Crazy. Must be due to interference with metal objects etc.