First flight crash

[Fly Dawg]

@Enrico BBB To add to the equation here. What "stick" mode were you using? The stick inputs appear reversed...IE Mode 1 or Mode 3. Note the full elevator during the climb.

 

[Enrico BBB]

I don't understand your question... It was the first launch ever... I didn't modify anything on the controller... I just followed instructions appeared on the screen about positioning before launch. So default. I only set C mode for safety reasons... I would have prevent surprises... It didn't work as you can see ))

 

[BudWalker]

That would suggest that no flight launched from that location would ever be safe.

I've always thought that magnetic distortion was quite localized--I mean centimeter range distances, a meter or two at most.

If your drone demands compass calibration, they say, you should first try moving your launch point a short distance. Hand launching, I've heard, is always safe from disruptive magnetic fields (providing you're not wearing or carrying something magnetic).

Is that not true? If the surrounding structures were the source of the disrupted geomagnetism, hand launching there would offer no advantage.

that's right. in most of the incidents we see the geomagnetic distortion is small. but, the extent depends on the mass and material causing the distortion. the extent also depends on the shape of the object and it's orientation w.r.t. the geomagnetic field.

hand launching works only when the AC is moved outside the extent.

 

[Fly Dawg]

I don't understand your question...

There are 3 stick modes. Normally by default, the left stick is throttle and rudder. This looks like it is in mode 2 or 3.
From the Mini-Manual......

 

[BudWalker]

@Enrico BBB To add to the equation here. What "stick" mode were you using? The stick inputs appear reversed...IE Mode 1 or Mode 3. Note the full elevator during the climb.

View attachment 88024

is this the right .txt? the one for this incident stops at around 70 secs.

 

[Fly Dawg]

is this the right .txt?

Sorry, wrong .txt I had 3MM .txt's in the same directory. My Bad.....

 

[Enrico BBB]

There are 3 stick modes. Normally by default, the left stick is throttle and rudder. This looks like it is in mode 2 or 3.
From the Mini-Manual......

View attachment 88025

Mode 2

 

[Thomas B]

Mode 2 is factory default... check the manual.

 

[Enrico BBB]

Mode 2 is factory default... check the manual.

Mode 2. I am 100% sure.

 

[Fly Dawg]

Mode 2. I am 100% sure.

You are correct. As noted above, I was looking at a different .txt file, not yours. My applogies for that.

 

[Enrico BBB]

You are correct. As noted above, I was looking at a different .txt file, not yours. My applogies for that.

No problem. I am really grateful for your help.

 

[slup]

You are correct. As noted above, I was looking at a different .txt file, not yours. My applogies for that.

Yeah ... mistakes happens even for the best

Have looked at the video alongside with the stick movements in AirData HD Flightplayer & 100% sure it's mode 2. From the fly away starts until the Mini crashes into the tree next to the house wall & falls next to a car the right stick never moves. The only oddity was the approx. 180 degree wrong heading ... which should have been visible in the map view in the Fly app.

One question to you deep analyzing guys ... This magnetic area ... should that have triggered a message to calibrate the compass?

 

[Enrico BBB]

Yeah ... mistakes happens even for the best

Have looked at the video alongside with the stick movements in AirData HD Flightplayer & 100% sure it's mode 2. From the fly away starts until the Mini crashes into the tree next to the house wall & falls next to a car the right stick never moves. The only oddity was the approx. 180 degree wrong heading ... which should have been visible in the map view in the Fly app.

Ok, but even with the wrong heading why the drone took decision by itself?
Wrong heading could give (I think) problems when piloting but, if you don't give any input why the drone fly away like crazy? 180 degree wrong heading could lead to drone going left instead of right or back instead of forward... But my drone suddenly went completely away...))
I am not so technical as you all but I still haven't understand if it was my fault or software or hardware fault...
Thank you.

 

[slup]

Don't really have the knowledge to explain way the drone reacted just as it did ... it was confused, but why it precisely took those decisions (bank right, gain speed) I can't tell.
Some thing happened with the heading as soon it left the ground ... the 180 degree rotation on the map starts 2 sec after takeoff & were completed 8 sec. after.

 

[BudWalker]

Yeah ... mistakes happens even for the best

Have looked at the video alongside with the stick movements in AirData HD Flightplayer & 100% sure it's mode 2. From the fly away starts until the Mini crashes into the tree next to the house wall & falls next to a car the right stick never moves. The only oddity was the approx. 180 degree wrong heading ... which should have been visible in the map view in the Fly app.

One question to you deep analyzing guys ... This magnetic area ... should that have triggered a message to calibrate the compass?

There is a compass error signal that I think, when true, will trigger the calibrate compass message. The compass error is true when the field strength exceeds or is less than the normal range. That normal range appears to be different for each platform. In this incident there was an interval before the flight where compass error was true. From the GPS data it looks like the MM was being moved around.


It's not possible to know if the field is distorted. The field strength is a reasonable proxy since a distorted field means that some locations will have a stronger field and other locations will have a weaker field.

 

[Prismatic]

Ok, but even with the wrong heading why the drone took decision by itself?
Wrong heading could give (I think) problems when piloting but, if you don't give any input why the drone fly away like crazy? 180 degree wrong heading could lead to drone going left instead of right or back instead of forward... But my drone suddenly went completely away...))
I am not so technical as you all but I still haven't understand if it was my fault or software or hardware fault...
Thank you.

Remember that the drone's flight control system attempts to hold its position using GPS (for its location) and the compass (for its orientation).

If it's hovering while facing east, say, and there's a breeze from the south, it'll drift a bit north. Observing the change in its location, it knows to apply compensating extra thrust in a southerly direction, e.g. to the starboard (rightward) to return to the hover-location.

But if--due to a misaligned compass--it's not facing east at all, but actually facing west, that starboard thrust moves it even further from the hover-location. The reasonable assumption is that the wind is stronger than the current extra thrust counteracts. So it applies more extra thrust, only to discover its location is even worse.

The errors compound, and the drone speeds off in the forlorn attempt to return to the intended location, but all the while applying exactly the wrong thrust to actually achieve that goal.

That's how compass errors cause flyaways. The pilot can't override the drone's flight control system, and helplessly watches the aircraft zoom into the distance, or into an obstacle. ?

 

[DanMan32]

I've touted that if GPS is good, AC should be able to detect and compensate for compass deviation by looking at GPS delta. I realize it can't do this before or on takeoff, but once it moves laterally, it can. Perhaps once compass error is detected based on GPS delta, pilot would be warned of the critical compass error and should be landed ASAP.

 

[Meta4]

I've touted that if GPS is good, AC should be able to detect and compensate for compass deviation by looking at GPS delta. I realize it can't do this before or on takeoff, but once it moves laterally, it can. Perhaps once compass error is detected based on GPS delta, pilot would be warned of the critical compass error and should be landed ASAP.

If you ever find yourself in a Yaw Error situation, you won't have time to land ASAP or the ability to control the drone to land it.

 

[DanMan32]

Under the current algorithm, I agree. But I believe the algorithm could be improved if on detecting the yaw error, the compass would be disregarded for flight control and GPS delta used for heading until it can sort out the compass error from GPS delta. Kind of like a dynamic compass calibration. There initially may be some uncontrolled flight, but after a max of a few feet the problem could be contained.

Now if the compass was in complete failure rather than a fixed deviation, compensation would be more difficult.

 

[Prismatic]

Under the current algorithm, I agree. But I believe the algorithm could be improved if on detecting the yaw error, the compass would be disregarded for flight control and GPS delta used for heading until it can sort out the compass error from GPS delta. Kind of like a dynamic compass calibration. There initially may be some uncontrolled flight, but after a max of a few feet the problem could be contained.

Now if the compass was in complete failure rather than a fixed deviation, compensation would be more difficult.

What about wind?