Mirek6 Posted at 2018-6-8 07:19
BrilhasMuito,

Why do you say "You gotta calibrate using the Wi-Fi. If you use OTG its most likely the calibration wont be accomplished".

As I said I could be completely wrong. I'm not quite sure. To clear things up I just posted a thread regarding this matter.

I gotta run more tests to try to prove this point but last week I tried several calibrations (more than 5) that couldnt complete. But as soon as I took the OTG off the calibration completed on the very first try.

It could be coincidence. I dont know. Gotta test it.
  

Mirek6 Posted at 2018-6-8 07:26
BrilhasMuito,

Just saw you reply to my question which you gave to DMX_MT.

Thank you Mirek,

Your reply regarding the OTG is very accurate in my opinion, see my reply to Brilhas above.., also when you talked about keeping distance from phone to calibrate the spark, and also technical details about the imu that it isn't sensitive to magnetic interference.

Mirek, so when you Calibrate the Spark, you say you need to keep the Phone at a distance away, so how can you know what the next step is ? Maybe print a diagram step by step, and wait the lights to flash to go to the next step, can you help me what the best way is please ?

Thank you !

BrilhasMuito Posted at 2018-6-8 07:27
As I said I could be completely wrong. I'm not quite sure. To clear things up I just posted a thread regarding this matter.

I gotta run more tests to try to prove this point but last week I tried several calibrations (more than 5) that couldnt complete. But as soon as I took the OTG off the calibration completed on the very first try.

I am sure it will work out well for you Brilhas, you are a Very Wise Pilot, I trust with all my heart !

Mirek6 Posted at 2018-6-8 07:26
BrilhasMuito,

Just saw you reply to my question which you gave to DMX_MT.

I always keep the phone away from the drone when calibrating the compass. I was in the middle of nowhere so I'm sure there was no close metal stuff. The interference shown in the app was ocillating but still on green.
I could be crazy but Im raising a point that happened to me which I think really strange. How do I do the calibration more than 5 times with no success but as soon as I take the OTG off it works on very first attempt? Coincidence? Could be I dont know.
I do get everything you say and I agree with you but its at least strange. I'm my view it deserves to be pointed and cleared.   

DMX_MT Posted at 2018-6-8 07:31
Thank you Mirek,

Your reply regarding the OTG is very accurate in my opinion, see my reply to Brilhas above.., also when you talked about keeping distance from phone to calibrate the spark, and also technical details about the imu that it isn't sensitive to magnetic interference.

There are just 2 simple steps. Once the first one is completed the status light flashes green so you know its time to do the second step. If it flashes red you know the first step failed.
   

BrilhasMuito Posted at 2018-6-8 08:34
There are just 2 simple steps. Once the first one is completed the status light flashes green so you know its time to do the second step. If it flashes red you know the first step failed.

I will do as you say, but for the Start I will write in my Notebook what to do and keep that in mind, I will put the Remote + Mobile far away from me. Is there a Minimum Distance eg. 5m Away ?

Brilhas my friend 'Introvert Speaks' did a really good video I like about the Compass Calibration and the way everyone should do it -

DMX_MT Posted at 2018-6-8 08:44
I will do as you say, but for the Start I will write in my Notebook what to do and keep that in mind, I will put the Remote + Mobile far away from me. Is there a Minimum Distance eg. 5m Away ?

Brilhas my friend 'Introvert Speaks' did a really good video I like about the Compass Calibration and the way everyone should do it -

No need to keep the phone so far. It just cant be really close to the drone. I always keep the RC and phone on the floor, walk a few steps from them then I start the calibration process. You can keep the phone in a way that you can read the screen.

DMX_MT Posted at 2018-6-8 08:44
I will do as you say, but for the Start I will write in my Notebook what to do and keep that in mind, I will put the Remote + Mobile far away from me. Is there a Minimum Distance eg. 5m Away ?

Brilhas my friend 'Introvert Speaks' did a really good video I like about the Compass Calibration and the way everyone should do it -

Im at the office, cant watch the video right now but will do as soon as possible.

BrilhasMuito Posted at 2018-6-8 09:07
No need to keep the phone so far. It just cant be really close to the drone. I always keep the RC and phone on the floor, walk a few steps from them then I start the calibration process. You can keep the phone in a way that you can read the screen.

Thank you for Clarifying this Brilhas ! I didn't know how far you need to leave the remote and phone !

I will try to calibrate wearing only the Brazilian Mini Tanga, so there will be no magnetic interference from metals etc.

Here is also a Link to another Hallmark007 Post -

Many useful info here too. Hallmark is one of the Best Pilots I follow in here !

I wish to Thank Him for all the Help and Time he dedicated to Help me learn !

------------------------------------------------------------------------------------------------------------------------------------

Avoid Crash due to Compass Interference

https://forum.dji.com/forum.php? ... 4222&fromuid=260008

DMX_MT Posted at 2018-6-8 09:11
Thank you for Clarifying this Brilhas ! I didn't know how far you need to leave the remote and phone !

I will try to calibrate wearing only the Brazilian Mini Tanga, so there will be no interference.

HAHAHAHAHAHHAHAHAHAHAHAHHAHAHAHAHA
LAUGH OUT AND REAAAALLY LOUD.
Can you imagine it becames the standart procedure for compass calibration? It'd at least strange! Waiting anxiously for the video m8. ahahahahha

Seriously, no need to keep the phone so far, 1 meter is more than enough.

BrilhasMuito Posted at 2018-6-8 09:21
HAHAHAHAHAHHAHAHAHAHAHAHHAHAHAHAHA
LAUGH OUT AND REAAAALLY LOUD.
Can you imagine it becames the standart procedure for compass calibration? It'd at least strange! Waiting anxiously for the video m8. ahahahahha

Hahhahahahahhahahahahahah !

Indeed it really helps I think. You know the belt has metal, the jeans has metal studs + zip etc..

DMX_MT Posted at 2018-6-8 09:25
Hahhahahahahhahahahahahah !

Indeed it really helps I think. You know the belt has metal, the jeans has metal studs + zip etc..

Noooooo man!
You can keep naked to go eat as well. Really good feeling! The good think is that no one will have the guts to ask you for tips.

BrilhasMuito Posted at 2018-6-8 09:34
Noooooo man!
You can keep nacked to go eat as well. Really good feeling! The good think is that no one will have the guts to ask you for tips.

Really ?

First I will start with the Calibrating.

DMX_MT Posted at 2018-6-8 09:38
Really ?

First I will send you the Video Calibrating, then tell me if I can go ahead eating with my physique...

Alriiiiiight!
Awaiting! Clock is ticking!

BrilhasMuito Posted at 2018-6-8 09:42
Alriiiiiight!
Awaiting! Clock is ticking!

They told me it will take 1 month to arrive here, but at least it will be July and it won't be cold.

DMX_MT Posted at 2018-6-8 09:44
I have to await the Thong from Copacabana, Rio de Janeiro.

They told me it will take 1 month to arrive here, but at least it will be July and it won't be cold.

Yes, we do that procedure in Brazil. And the compass always calibrate, always! hahahahahaha

BrilhasMuito Posted at 2018-6-8 09:50
Yes, we do that procedure in Brazil. And the compass always calibrate, always! hahahahahaha

Thanks for always keeping your Comments so Positive.

Good video. Explains well what is required. The Introvert keeps his Spark about a meter away from his iPad - that's more than enough.
He also explains, what other people did not understand (other threads), that DJI GO showing all is OK with compass does not mean that it really is. Which brings the point about re-calibrating compass if moving to far away location (several hundred kilometers away) no matter what DJI Go says. I know that some newer drones have magnetic declination maps programmed in which makes this unnecessary, but Spark does not.

I was slightly surprised that he was surprised that putting hard drive over Spark caused interference even though there was no electric current. Of course it would. Hard drives have magnetic plates which emit quite strong magnetic field. Same as trying to put a magnet on top of Spark. No current required :-).

Looking forward to your Thong calibration video :-).

Mirek6 Posted at 2018-6-8 11:34
Good video. Explains well what is required. The Introvert keeps his Spark about a meter away from his iPad - that's more than enough.
He also explains, what other people did not understand (other threads), that DJI GO showing all is OK with compass does not mean that it really is. Which brings the point about re-calibrating compass if moving to far away location (several hundred kilometers away) no matter what DJI Go says. I know that some newer drones have magnetic declination maps programmed in which makes this unnecessary, but Spark does not.

Thank you Mirek, so in your opinion I live in Malta, a Very Small Island in the Mediterranean.

You suggest if I go from one place to another about maybe 1km away, I re-calibrate the compass or I just check it with the DJI Go4 App that the heading is matching where the Spark is facing ?

I will keep the remote over 1m away, like You and Brilhas told me.

DMX_MT Posted at 2018-6-8 14:34
Thank you Mirek, so in your opinion I live in Malta, a Very Small Island in the Mediterranean.

You suggest if I go from one place to another about maybe 1km away, I re-calibrate the compass or I just check it with the DJI Go4 App that the heading is matching where the Spark is facing ?

No - I never suggested to re-calibrate compass if you move 1 km.

What I suggested is that if you go long distances - like several hundred kilometres - than re-calibrate compass because there may be significant difference in magnetic declination.

BTW. Malta's magnetic declination is very small - about 3 degrees - and Malta is way to small that there is any difference between any two points on the island. I would calibrate my compass once if I flew there and than l;eave it while visiting the island.

I live in Canada - when travelling long distances the difference in magnetic declination may be huge. I mean - extreme.

Mirek6 Posted at 2018-6-8 17:24
No - I never suggested to re-calibrate compass if you move 1 km.

What I suggested is that if you go long distances - like several hundred kilometres - than re-calibrate compass because there may be significant difference in magnetic declination.

The Information you gave me Mirek is - GOLD - for me !

You and Brilhas helped me a lot, and I am so much Obligated !

Now I understand that if I move several kms I must re-calibrate. Malta is very small as you say. So I won't re-calibrate.

I know what you mean by Large Distance in Canada, I haven't been but my Wife's Family is mostly Canadian. Some live in Ontario (Toronto) and others like in British Columbia (Vancouver). Its about a 6hr flight ! From Malta to Siciliy its just 20mins flight.


Just one last question please -

''If I won't fly the spark, lets say for 1 month or 3 months, do you think its best to do Compass and IMU Calibration again, please ?''

Thank you !

No. No need to calibrate if you did that before. It does not matter if you did not fly Spark for a few months. Compass or IMU will stay the same.

Only calibrate in the following situations:

1. First time after you bought Spark.
2. Calibrate compass if you traveled very long distances - several hundred kilometers or more (you must do this because magnetic declination will most likely be different).
3. When DJI GO asks you to do so.
4. When Speak starts to behave in weird ways.

Otherwise just enjoy your flights and do not recalibrate.

There is old saying in English - if it ain't broken don't fix it. It means basically - if everything is fine do not try to correct that.

Spark is a marvel of technology. Trust it.

Happy flying.

Mirek6 Posted at 2018-6-9 19:34
No. No need to calibrate if you did that before. It does not matter if you did not fly Spark for a few months. Compass or IMU will stay the same.

Only calibrate in the following situations:

Thank you Mirek, I will keep these Tips on my Notebook.

They are very useful for me, your Help was so much Appreciated !

Thank you again ! Happy I got in a conversation with You Mate.

Thanks to Joe, this is another Important Video regarding the IMU -

Thank you DMX_MT. This video has one new element I never thought about - it shows that the surface on which you calibrate IMU need to be perfectly level.
This bring very interesting question which I posted to "Introvert Speaks" on Youtube.

Here is my observation and question - I wonder if anybody on the forum can give a dfinite answer to this:

I saw that you are making sure that Spark is perfectly level when calibrating IMU. This calls for the question, can badly calibrated IMU cause Spark to be slightly tilted (pitch or roll) while flying? Or IMU does not control tilt but cares about acceleration only. I would tend to believe that it does control tilt since it has gyroscopes. Now, the important part. If the Spark is tilted while flying due to badly calibrated or un-calibrated IMU, what happens when it drops to ATTI mode ( when it has compass or yaw errors or weak GPS signal)?. In ATTI mode Spark is subject to environmental factors such as wind but many Spark users reported that Spark starts to fly away even without wind. This could be consistent with tilt. If Spark is tilted due to bad IMU calibration and gets into ATTI, I presume it could start to fly away on its own in a direction of tilt. Is my logic correct? What do you think?

Mirek6 Posted at 2018-6-11 05:43
Thank you DMX_MT. This video has one new element I never thought about - it shows that the surface on which you calibrate IMU need to be perfectly level.
This bring very interesting question which I posted to "Introvert Speaks" on Youtube.

I think you have a Good Point there.

Though when I talked to some Pilots re the IMU Calibration they just told me you have to find a very flat surface, if it is tilted when calibrated or you calibrate it on an uneven surface the Program will just show you a Failed Calibration.

His Personal Homepage is this - He is a Really Wonderful Guy to speak to ! I really like him !

https://forum.dji.com/home.php?m ... uuid=fd2d9b2a379ae9

Yes - this makes sense.
With an advanced piece of technology like Spark, DJI engineers probably included some horizontal level sensors, so slight deviations from completely horizontal position while calibrating IMU may not cause trouble, as long as the surface is fairly level and flat. Such sensors could trip IMU calibration failure if it is not so.

However, my question to this forum, DJI moderators and "Introvert Speaks" still holds.
And the question is: Can un-calibrated or badly calibrated IMU result in Spark tilt (roll or pitch) while flying which, in turn,could cause Spark fly-away when in ATTI mode?

Hey,

I answered my own question while researching yesterday on how accelerometers in IMU work and the exact physics of quadcopter flight.
In summary: accelerometers in IMU are responsible for keeping AC level (roll and pitch), gyroscopes control yaw. Since accelerometers work in 3 dimensional space they need to be calibrated along three axis. This is exactly what is happening during IMU calibration - Spark is put level on each of 3 axis - twice. This way IMU "learns" what doe mean to be "level".
Badly calibrated IMU or IMU which does not function properly may not be able to keep AC level in the air. It may "think" that AC is "level" while it is not. AC may be slightly tilted one direction or the other. Thus, due to pure law of physics, AC will start flying in the direction of tilt - even in perfectly calm weather with no wind. If Spark is in P-GPS mode this is not a problem. GPS unit will report position change and the revers force will be automatically applied to keep it in place. However, in ATTI mode, no corrective action will be taken. The drone will simply start drifting and accelerating in the direction of tilt until air pressure caused by movement  equalizes the forces and acceleration stops and movement continues with constant speed.

In the end - yes, if IMU fails (its measurements are imprecise) for whatever reason, AC can fly-away on its own (without any input from the pilot) when it drops to ATTI mode. Even with no wind.  Only pilot's conscious manual action can save the day.

Regarding "Position hold" video earlier in this thread.

For those who would like to understand a bit better why, when you do not touch the sticks the AC returns to the same position even if you drag it by force to some other place, but, the moment you touch the sticks it "forgets" its previous co-ordinates.

AC keeps track of two positions: Commanded position and Physical position. Commanded position is where, it thinks, you asked it to be (by using your stick movements and compass) and Physical position is where it really is (using GPS co-ordinates). When you put your AC in hover over particular point in GPS mode, you "commanded" it to this spot and it flew there and confirmed that his physical position agrees with you commanded position. If it is not quite right, it will adjust it - this is what you see in the video when drone is "hunting" for a correct position. In the end its commanded position = physical position and it will stay put.  

When you drag your drone out of its hover position (by catching it and physically moving to different spot while it is still flying) without touching your sticks, your are not changing Commanded position but you are changing Physical position. The drone will start to fight with you and pull in the direction of the Commanded position (which did not change). As soon as you release it, it will fly to the Commanded position.

However, when you drag your drone and than move your sticks slightly, the Commanded position gets recalculated based on where you are at this particular moment and what you did with sticks. If the movement is very slight, the new commanded position is almost in the spot where you are with your "fighting to fly" drone. Your drone immediately recalculates that its physical position now equals commanded position and stays in place.

This is what we witnessed in that video.

Mirek6 Posted at 2018-6-12 05:23
Hey,

I answered my own question while researching yesterday on how accelerometers in IMU work and the exact physics of quadcopter flight.

Very interesting deep analysis !

Thank you very much Mirek. Much Obligated for sharing all this useful information on the IMU.

Mirek6 Posted at 2018-6-12 05:40
Regarding "Position hold" video earlier in this thread.

For those who would like to understand a bit better why, when you do not touch the sticks the AC returns to the same position even if you drag it by force to some other place, but, the moment you touch the sticks it "forgets" its previous co-ordinates.

Thanks also for this.

You did a deep research on the Hold Position too, I really wish to Thank You !

The Physical Force can be the Wind, and when in P-GPS the Hold Position is a very good feature which keeps the Drone in the last known GPS Co-ordinates and Hover.

Thats is why it is 'SO IMPORTANT' that New Pilots know these things and read about these topic to avoid Panicking. Also VLOS (Visual Line of Sight) is also very important, just in case you lose your Feed during an ATTI Situation.

Thank you Mirek !

Call me simple, but the compass, altimeter, barometer etc need calibration during a typical Commercial flight before take off.   Spark, like any modern Jet with auto pilot may be similar? ...    If I take off without collecting all weather info & no  GPS link =  dumb pilot = CRASH...   Bad data - NO FLY unless you have manual control & A Home Point. What else can Spark do?

Sparkz71 Posted at 2018-6-14 06:22
Call me simple, but the compass, altimeter, barometer etc need calibration during a typical Commercial flight before take off.   Spark, like any modern Jet with auto pilot may be similar? ...    If I take off without collecting all weather info & no  GPS link =  dumb pilot = CRASH...  The speed data is wrong as supplied, I see a different story when comparing data maps.
Take off beside a warehouse entry walkway with metal all over the place? That is the problem, Check IMU & compass. The manual includes pre-cautions before flight.
Are you flying with 0 experience. Bad data - NO FLY unless you have manual control & A Home Point. What else can Spark do? Crash below or land near the last GPS co-ords' - all recorded in Spark once recovered. I'm not saying  Spark is right - Spark needs basic improvements, Half the problem is translation  This is very obvious when DJI reply & misunderstand the English Language at times. Funny, but no help nor answer.

Thank you for sharing your Opinion.

In the beginning of the Forum I made some - PRE-Flight Checklist links posted from my friend Hallmark007.

I am a Commercial Pilot and agree 100% with your comment.

Though many Pilots say - If it ain't broken don't try to fix it.

So a basic Pre-Flight Routine - posted another link from Hallmark007 - About Compass Errors will give you a Safer Flight.

DMX_MT Posted at 2018-6-14 06:38
Thank you for sharing your Opinion.

In the beginning of the Forum I made some - PRE-Flight Checklist links posted from my friend Hallmark007.

Thank you for replying.  Every information is helpful. I've played with flight simulators from Microsoft for years & flown in a real glider.... up & down with the wind forces adjusting height,  Then jump into a commercial passenger plane & feel the turbulence between flight levels as the wind changes, the wings 'bounce'.  The pre flight checklist is half the process. Safe to take off, but is it safe to fly? Check ongoing weather & wind conditions during the planned flight time & fly accordingly.  Avoid fog, rain or any other reflective surfaces. Set to RTH height above trees or whatever.

Happy Flying!

Sparkz71 Posted at 2018-6-17 12:49
Thank you for replying.  Every information is helpful. I've played with flight simulators from Microsoft for years & flown in a real glider.... up & down with the wind forces adjusting height,  Then jump into a commercial passenger plane & feel the turbulence between flight levels as the wind changes, the wings 'bounce'.  The pre flight checklist is half the process. Safe to take off, but is it safe to fly? Check ongoing weather & wind conditions during the planned flight time & fly accordingly.  Avoid fog, rain or any other reflective surfaces. Set to RTH height above trees or whatever.

Happy Flying!

Agree 100% with you Sparkz !

It's nice talking to you Sir !

Mirek6 Posted at 2018-6-8 11:34
Good video. Explains well what is required. The Introvert keeps his Spark about a meter away from his iPad - that's more than enough.
He also explains, what other people did not understand (other threads), that DJI GO showing all is OK with compass does not mean that it really is. Which brings the point about re-calibrating compass if moving to far away location (several hundred kilometers away) no matter what DJI Go says. I know that some newer drones have magnetic declination maps programmed in which makes this unnecessary, but Spark does not.

Specifically: moves between 2 strong permanent magnets, head positioning coils. The disks are barely magnetic ...

Jakab Gipsz Posted at 2018-6-17 14:30
Specifically: moves between 2 strong permanent magnets, head positioning coils. The disks are barely magnetic ...

Jakab,

I am not sure what disks you refer to by saying "disks are barely magnetic". Please let  me know.

Mirek6 Posted at 2018-6-17 15:56
Jakab,

I am not sure what disks you refer to by saying "disks are barely magnetic". Please let  me know.

The rotating discs are immensely magnetic. But there are two strong permanent magnets in the unit that moves the head. They are strong.

Jakab Gipsz Posted at 2018-6-17 16:03
The rotating discs are immensely magnetic. But there are two strong permanent magnets in the unit that moves the head. They are strong.https://www.youtube.com/watch?v=uSjxLH7vWUM

Yes - absolutely. This is how information is written and stored on hard drive. Magnetic media written to by magnetic heads.