ianwood
Taco Wrangler
Declination has nothing to do with calibration. You're thinking of inclination and deviation.
Everyone please have a read of this: Compass Calibration, A Complete Primer
I wrote it for the P2 but pretty much all of it applies. If you take off from a source with a localized magnetic field, you will end up in trouble. If you calibrate in an area with a localized magnetic field, you will be in trouble.
Blade, one thing I'm not clear on though is the end of Tyler's video. It dunks itself into the water at high speed. Do you think that is all due to the compass at that point?
No problem.. First time I learned about this was taking off from a manhole cover with a Y6 a few years back. I was doing some filming for the sewer department and thought it would be cool to do a straight down shot from the manhole cover that had it's number on it. Took off in manual hovered and got the shot.. Then at about 30' I switched into GPS and guess what? She took due north and a really crazy speed. switched out of gps and took control over the craft and landed. Rebooted the craft away from the metal and she was perfect again, only time I EVER had an issue with that craft.
The y6 with the it's landing gear and GPS mast must have had at least 2' separation from the metal and it still affected the compass. Now imagine the poor little p3 with the compass in it's leg, its at ground level very close to everything.
Yes immediate, compass errors from the concrete you took off from. Walkways usually have more rebar in them than say a slab.
I don't know, that's what I'm not sure of? with all the switch throwing and stuff I don't know if the compass stayed in degradation mode or tried listening to the false data...
2 minutes left on hold..
hopefully someone at DJI is nice and helps.. whats your thoughts? anything I should say, just open a case and submit logs and video? do they RMA if the Phantom is lost? (only if you know or can help)
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I think we (not trying to speak for anyone else) so, I know *I* don't have issue with compass calibration, and *I* understand the what and why it's done...
...the question is more of a how much or how little EMF causes these issues we're discussing. That's all.
I'm surprised that IF a bit of concrete rebar 4" under the surface can effect these things, then maybe a compass on the landing gear isn't such a good design feature? I mean, I would think there is more EMF from the battery and electronic components (all within 4" from the compass) than a piece of rebar 4" under the surface of concrete (so about 6" away from compass). But that's why I'm here, to learn!
Seems silly DJI would do it that way IF it was that sensitive is all I'm getting at I guess...
But I'm totally OK with "better safe than sorry".
It's all good.
That's what calibration takes into account, this is why on other craft you should make sure everything is powered on, including the camera. This gives the compass a known basis.
On a craft this small there is nowhere else to put the compass..
The compass is sensitive enough to not calibrate when I have my belt on. I was going to create a simple launch platform to keep dirt and debris away from camera, now it looks like it will serve another purpose lol
When the craft is lost it's a case by case.. You would have to ask the phone support rep to get a definite answer.
ianwood
Taco Wrangler
4" from rebar is too close. it will have a magnetic field and depending on its composition and what it has been exposed to, that field can be plenty strong.
The reason the compass is on the leg is because you have four motors full of magnets!
The reason the compass is on the leg is because you have four motors full of magnets!
Why did you do a CSC inflight? The motors will turn off in doing so. You know this correct?
Sorry to be a noob and state the obvious but I should be getting my phantom soon and all this has me a little worried about flying it.
In summary from this post I have learnt,
Don't take off from anywhere there could be magnetic interference.
Do not calibrate the compass each flight unless you have changed location significantly or maybe if you have changed environment i.e inside, warehouse with possible magnetic interference?
Once you are in the air, hover for a bit to see if anything is a bit wonky.
If you have a crash its not a good idea to push the boundrys until you are sure the phantom is fine.
Some of this is common sense but for those that are totally new to it all even the obvious can be missed.
In summary from this post I have learnt,
Don't take off from anywhere there could be magnetic interference.
Do not calibrate the compass each flight unless you have changed location significantly or maybe if you have changed environment i.e inside, warehouse with possible magnetic interference?
Once you are in the air, hover for a bit to see if anything is a bit wonky.
If you have a crash its not a good idea to push the boundrys until you are sure the phantom is fine.
Some of this is common sense but for those that are totally new to it all even the obvious can be missed.
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The reason the compass is on the leg is because you have four motors full of magnets!
Yeah yeah, but you can still put it up higher and shield it from other onboard EMF.
Which brings me to - if it IS indeed so sensitive and has to be down so low, why isn't it better shielded?
I dunno'. One thing I do know is, I'm pretty darn sure I'm gonna like this place!
Very enlightening thread. Thanks all.
Blade, I would ask you to look at DJI web site video that basically says take it out of the box and fly it over the ocean, this is so not true. You have to update it, Bin root, root bin,,,, then God forbid you are in flight and stick the sticks in opposite corners the power shuts off, with all the fail safes, battery low, out of range, and the bird's self preservation it will still fall from the sky.
There is NEVER any reason to issue a CSC in flight unless its for emergency . Just like any device you should read the manual as advised.
You really need to look at the commands given when you issue a CSC. Full rudder, Full throttle down, full elevator back and full deflection on aileron.. Why would a pilot give such commands in flight?
Regarding updates and such.. Pretty much any new technology that you buy will require a fw update before use... Everything from cell phones to smart TV's, even that computer your typing on!
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ianwood
Taco Wrangler
It is shielded but only so much because it needs to detect the earth's magnetic field.
It's actually pretty easy to avoid local magnetic fields when taking off. I fly in urban landscapes all the time. I find that my case is just high enough to keep me safe on most concrete surfaces. However, I check it every time and on a number of occasions I've moved because I didn't like what I saw. I use an app on my phone that gives me the total field for the phone's magnetometer using a sum of squares algorithm.
I raise and lower the phone being careful to hold it in exactly the same orientation the whole time. If the value changes too much, I know there's a local field and move elsewhere.
It's actually pretty easy to avoid local magnetic fields when taking off. I fly in urban landscapes all the time. I find that my case is just high enough to keep me safe on most concrete surfaces. However, I check it every time and on a number of occasions I've moved because I didn't like what I saw. I use an app on my phone that gives me the total field for the phone's magnetometer using a sum of squares algorithm.
I raise and lower the phone being careful to hold it in exactly the same orientation the whole time. If the value changes too much, I know there's a local field and move elsewhere.
Just sent off the forms and Data, in any case hopefully it will help everyone if there is any useful data for future updates if there is an issue.
Hopefully if it isn't user error then a mutually beneficial option is reached
