My bad or not ?

[Mazdaman323lx]

Yes quite possibly . Never had any issues launching from there before . Just to clarify, would this issue have occurred had I waited for the home point lock ?

 

[Mazdaman323lx]

100% pilot error I'm afraid.

Yaw error but no need for the FC to hold position (nothing external that affects the drone) = nothing happens.
Yaw error with a need for the FC to hold position... the FC will apply thrust on the wrong motors as it have the wrong info about the drones heading direction. With this the positional error grows instead of getting smaller... the FC tries again even more forceful... & everything repeats over & over again ... & the drone flies away, often exceeding both specified speeds & tilt angles.

Might add... this is the main danger with GPS drones, they seems to be flying all by there own & in most cases an ignorant pilot will be saved by the automation. But if the flight controller have the wrong information (from a deflected compass) it will take wrong decisions. ALWAYS confirm that the drone icon on the app map points in the same direction as the drone does in reality before take off... if not POWER down the drone move to another spot & try again.

It's a bit like rudder reversal on the 737s years ago so? ,
I'll take the hit I have care refresh so not the end of the world but i hate using it for instances where I don't actually fly into something. Thanks for the analysis. Much appreciated. Nice to know what went wrong to avoid it in the future.

 

[Mazdaman323lx]

Last question guys , thanks for all the help , but , had I hand launched it from the same spot , would that 3 or so feet be enough to compensate for the magnetic Interference in the concrete?

 

[slup]

Last question guys , thanks for all the help , but , had I hand launched it from the same spot , would that 3 or so feet be enough to compensate for the magnetic Interference in the concrete?

What matters is where the drone is when you power it on not launch, it's during power on the IMU gets initialized by the compass... don't take a chance trying to pinpoint a certain way to avoid a deflected compass, when you rather should look & confirm before launch that everything is good to go in the app map as we told you in earlier posts?

 

[Meta4]

Last question guys , thanks for all the help , but , had I hand launched it from the same spot , would that 3 or so feet be enough to compensate for the magnetic Interference in the concrete?

Hand launching (inc powering up in the hand) probably would have prevented the issue at that spot

Launching from reinforced concrete surfaces is the most common way to induce yaw errors.
Flyers often say "but I've launched from there many times..."
You cannot see the steel and a matter of an inch or less"might be all it takes to deflect the compass sensor and cause the problem.

Avoiding flying from reinforced concrete is a good practice.
But if you have to, then check the orientation of the drone icon and that it's facing the same direction as the actual drone.

 

[Dave Maine]

There is sometimes metal under asphalt as well, as metal braces under wooden decks. The only safe procedure is the one mentioned above - verifying that the drone’s compass lines up with it’s actual direction.

 

[KB9Radio]

Concrete pier .

I find the worst surface to launch from is concrete, even though everyone including me would love to. Concrete almost always has rebar and/or wire mesh in it, which messes with the compass. I picked up a nice hoop type nylon landing pad and always launch from dirt or grass. Anything that does not contain steel nearby.

 

[slup]

I find the worst surface to launch from is concrete, even though everyone including me would love to. Concrete almost always has rebar and/or wire mesh in it, which messes with the compass. I picked up a nice hoop type nylon landing pad and always launch from dirt or grass. Anything that does not contain steel nearby.

If we agree that "Launching" & "Powering on" the drone is 2 very different thing's... it's then no problem to launch your drone from concrete, it's even totally risk free to do that right on top of a magnet.

A yaw error is generated in the moment you power on your drone... it's there the IMU "peaks" at the compass & use it's value to know in what direction your drone points. So... if the compass is deflected in this moment the IMU will inherit this deflection.

To avoid this compass deflection as much as possible you should power it on in your outstretched hand (no watches, rings, bracelets or metal zippers)... once the live view shows up in the app, the dangerous moment is over & you can place your drone for a launch where ever you want.

And before you launch the drone sky-high you always confirm that everything is good by comparing the drones direction in reality with how the drone icon is pointing on the map in the app (if the drone have a house/road in front of it, the app map icon should indicate the same).

So 3 thing's to add as a procedure...

1. Power the drone in your hand, not standing on something (this will probably save you the hassle to re-powering your drone later if the "reality vs. map check" fail).

2. ALWAYS confirm the drones pointing direction on the app map & make sure it aligns with how the drone is pointing in reality.

3. Put the drone down on a suitable launch spot, start the motors... & take-off.

IMPORTANT... if the confirmation in step 2 fails, you must power cycle the drone in order to set off a new IMU initialization (preferably you do this in another way/place than the first power on so you escapes the magnetic interference... then repeat point 2... & you repeat everything until the map/reality directions aligns.)

 

[Cafguy]

There is also metallic aggregate in concrete that can also cause problems- Best to use a landing pad and stay away from the stuff if possible. and I always tell people to stear clear of it when doing any calibrations.

 

[BudWalker]

Then you've been lucky & not experienced a yaw error until this flight... imagine that you didn't confirm the drones direction compared to the drone icon on the app map before taking off?

Just out from the .txt log I'm pretty sure that my initial thought was correct... all went good initially in the flight as the FC didn't have to counter wind drift initially (low height), then later couldn't as the drone went into Atti mode ( blue background GPS mode, Pink Atti mode).

But 14,5sec after launch you got 8sats... but even though the FC graded the positional reliability to a 2 (out of 5), it most probably weighed in that data to some extent anyway. Then at 20sec you releases the sticks, but the drone continued to tilt & at 24,8sec all went haywire... & your drone ended up with an 70 degree tilt (combined pitch & roll)... there it couldn't hold the height anymore & the drone speeded away downwards.

If you want us to more exactly confirm the yaw error you need to share the mobile device .DAT log ending with FLY210.DAT.

View attachment 171014



Read the above... & note what happens at 14,5sec.

I think all was going OK in the first 7.5 secs because the vision system was being used for position and velocities. During this interval the flyState field was "P-GPS" which really means not ATTI. It doesn't necessarily mean GPS was being used for position and velocities data. In this case those data were being provided by the vision system. After the vision system stopped the flyState became ATTI

Puzzling, to me at least, is the roll value of -70.0°. Even though the Mini3 was in ATTI mode the Flight Controller shouldn't have commanded such a large roll. @Mazdaman323lx sure would be interesting to see the .DAT if you can retrieve it.

 

[KB9Radio]

If we agree that "Launching" & "Powering on" the drone is 2 very different thing's... it's then no problem to launch your drone from concrete, it's even totally risk free to do that right on top of a magnet.

A yaw error is generated in the moment you power on your drone... it's there the IMU "peaks" at the compass & use it's value to know in what direction your drone points. So... if the compass is deflected in this moment the IMU will inherit this deflection.

To avoid this compass deflection as much as possible you should power it on in your outstretched hand (no watches, rings, bracelets or metal zippers)... once the live view shows up in the app, the dangerous moment is over & you can place your drone for a launch where ever you want.

And before you launch the drone sky-high you always confirm that everything is good by comparing the drones direction in reality with how the drone icon is pointing on the map in the app (if the drone have a house/road in front of it, the app map icon should indicate the same).

So 3 thing's to add as a procedure...

1. Power the drone in your hand, not standing on something (this will probably save you the hassle to re-powering your drone later if the "reality vs. map check" fail).

2. ALWAYS confirm the drones pointing direction on the app map & make sure it aligns with how the drone is pointing in reality.

3. Put the drone down on a suitable launch spot, start the motors... & take-off.

IMPORTANT... if the confirmation in step 2 fails, you must power cycle the drone in order to set off a new IMU initialization (preferably you do this in another way/place than the first power on so you escapes the magnetic interference... then repeat point 2... & you repeat everything until the map/reality directions aligns.)

All true, however if you just put it on a safe surface to begin with the problem is solved. I've been launching (excuse me, powering & launching) off a 4' diameter pad now for many years with no issues. I originally did the concrete thing or worse yet, vehicle hood/roof. I would often get prompted to do a compass calibration, and just chalked it up as due to a new location or something. After a period of time I figured out it was due to nearby magnetic interference of one kind or another. I purchased the pad that I use so I wouldn't be directly on the dirt, snow, grass and so on. Since I purchased the pad and have been taking off on the dirt/lawn I have never been prompted to calibrate again, that has been at least 2-3 years and traveled 1000's of miles from my home. So I guess it's the old saying "whatever works" but at any rate, don't turn on your drone (I turn on and launch from the same spot) where there's a good chance of magnetic interference. It will cause trouble.

 

[MS Coast]

All true, however if you just put it on a safe surface to begin with the problem is solved.

Well, what seems like a safe surface to our senses may still confuse the compass.

I did a series of startups with a 10" iron spike in various positions directly beneath and close around the drone and found no problems at all. A tiny (1/8" x 1/4") magnet from a discarded electric toothbrush head severely biased the compass. Another series of startups on the roof of my car showed no problems other than one location above the driver side rear door. I have no explanation for the difference.

To be certain all is well , I check the compass against reality on every takeoff, even the ones on seemingly safe surfaces. It's five seconds per takeoff well spent.

 

[slup]

...Since I purchased the pad and have been taking off on the dirt/lawn I have never been prompted to calibrate again, that has been at least 2-3 years and traveled 1000's of miles from my home. So I guess it's the old saying "whatever works..

Of course you handle it in the way you want... but it never hurts to know how thing's actually works.

And another thing... Have been investigating incidents here at the forum for years now, & looked into numerous of yaw error cases. What nearly all cases have in common is that the OP's very often claimed taking off from that particular spot for numerous of times before without any incident... the take away seems to be, that the great number of times they have been lucky doesn't help that one time they aren't anymore.

And to give you another bit of knowledge in regards to what you write... the calibration prompts in the app comes when the magnetic interference have reached a threshold. This threshold is usually much higher interference wise than what's needed to deflect the compass enough to induce a yaw error with a following flyaway. So that you don't get a prompt to calibrate doesn't guarantee that you doesn't have a yaw error after the power on sequence.

 

[4006448]

Reading this thread has been educational. Thanks to all those who posted. Sorry about the fly away, but I’ve learned from it.

 

[EricJT]

Of course you handle it in the way you want... but it never hurts to know how thing's actually works.

And another thing... Have been investigating incidents here at the forum for years now, & looked into numerous of yaw error cases. What nearly all cases have in common is that the OP's very often claimed taking off from that particular spot for numerous of times before without any incident... the take away seems to be, that the great number of times they have been lucky doesn't help that one time they aren't anymore.

Somewhat akin to Russian Roulette.....a heck of an adrenalin rush the majority of times, but fatal when your luck runs out.

 

[Mazdaman323lx]

I think all was going OK in the first 7.5 secs because the vision system was being used for position and velocities. During this interval the flyState field was "P-GPS" which really means not ATTI. It doesn't necessarily mean GPS was being used for position and velocities data. In this case those data were being provided by the vision system. After the vision system stopped the flyState became ATTI

Puzzling, to me at least, is the roll value of -70.0°. Even though the Mini3 was in ATTI mode the Flight Controller shouldn't have commanded such a large roll. @Mazdaman323lx sure would be interesting to see the .DAT if you can retrieve it.

I'll try to get it to you . I'm still mystified as to why the drone went down from 30 meters up . I can understand it moving in the wrong direction , laterally , but it went down at a steep angle and at a crazy speed , as if the hand of god was pushing it out of the sky .

 

[RodPad]

I looked through this thread closer and there is a lot of stuff that acknowledge but really don't?
In this post it states "Concrete pier"

My bad or not ?

Ok , before we begin , yes I took off with my mini 3 pro before acquiring satellites , however it seem slow to lock in so I figured i'd fly up to 30 m where it would lock on easier and a distance of 100m away. I was about 80m away , flying away from myself over a wide river , still in atti mode...

mavicpilots.com

Was it that flight or a previous one?

The log of DJI Flight Log Viewer - PhantomHelp.com
Shows me the goofy thing again where I can tell it was on earth, even in another browser.
I another thing that comes and goes.

Rod ..

 

[Yorkshire_Pud]

I looked through this thread closer and there is a lot of stuff that acknowledge but really don't?
In this post it states "Concrete pier"

My bad or not ?

Ok , before we begin , yes I took off with my mini 3 pro before acquiring satellites , however it seem slow to lock in so I figured i'd fly up to 30 m where it would lock on easier and a distance of 100m away. I was about 80m away , flying away from myself over a wide river , still in atti mode...

mavicpilots.com

Was it that flight or a previous one?

The log of DJI Flight Log Viewer - PhantomHelp.com
Shows me the goofy thing again where I can tell it was on earth, even in another browser.
I another thing that comes and goes.

Rod ..

The Gulf of Guinea thing is due to zero GPS, the cordinates of the point are 0,0.

 

[Mazdaman323lx]

I looked through this thread closer and there is a lot of stuff that acknowledge but really don't?
In this post it states "Concrete pier"

My bad or not ?

Ok , before we begin , yes I took off with my mini 3 pro before acquiring satellites , however it seem slow to lock in so I figured i'd fly up to 30 m where it would lock on easier and a distance of 100m away. I was about 80m away , flying away from myself over a wide river , still in atti mode...

mavicpilots.com

Was it that flight or a previous one?

The log of DJI Flight Log Viewer - PhantomHelp.com
Shows me the goofy thing again where I can tell it was on earth, even in another browser.
I another thing that comes and goes.

Rod ..

Yes , it was that flight . Took off from a old concrete pier at the riverside .

 

[RodPad]

@Yorkshire_Pud @Mazdaman323lx
Thanks!

This goofy thing that it happens, seems like @Meta4 and I on different thread said it happens to him also.

I need to figure out this on my side.
I got the answer to the question!

Rod ..