Please select Into the mobile phone version | Continue to access the computer ver.
When and how to calibrate the IMU -- DJI Phantom 4
12Next >
23617 41 2016-6-1 02:05:12
DJI-Paladin
DJI team
Hong Kong
Offline

Special thanks to Tom's Tech Time!


2016-6-1 02:05:12
Use props
dobmatt
Second Officer
Offline

Dear DJI-Paladin, again and again somebody is recommending so called "cool IMU calibration" procedure without explanation why we need to chill down the drone before. All we know that it will get rid of Warming Up sign on Go app screen before take off. This issue is driving me crazy ...

Please, do me a favor: talk to tech people at DJI and ask what is warming up for. Ask them what chilling the drone before IMU calibration does to the system and why this method is NOT mentioned in manual.

Let's get it clear once and forever, I'm begging ...
2016-6-5 13:12:21
Use props
rodger
Captain
Flight distance : 411485
  • >>>
United States
Offline

dobmatt Posted at 2016-6-5 17:12
Dear DJI-Paladin, again and again somebody is recommending so called "cool IMU calibration" procedur ...

Maybe this will help? In electronics and many other types of equipment the term "Cold" refers to the equipment being at the ambient temperature. In other words the equipment has not been on for an extended period of time. We want to do our calibration at the ambient temp. due to the fact that we want everything to be in spec. when we turn it on for the first time after it was at rest.

If we do a calibration after the equipment has been running for a while the equipment has come up to a running temp. (Warm or hot") and the electronics will adjust at that temp.
When the term "warm up" is used we mean that the electronics and sensors have been excited for a short bit of time. You will see a notice that the "IMU" is warming up. In the warm up process all of the senors, Gyro's etc. have become excited (alive with voltage applied).

If you were to literrally cool your Phantom to below ambient temp. in a refrigerator as an extreme example and do the "IMU" calibration it will take much longer for the electronics and sensors to stabilise at ambient temp and your warm up time will be greatly extended.

The short of it is: Leave everything powered down far an extended period of time with the battery removed to let it come to ambient temp. and ambient air temp. to circulate through your Phantom, let's say an hour to be safe and then insert your charged battery. Have your Phantom on a hard LEVEL surface! With everything on and all warnings off perform your "IMU" calibration. Now lets go flying!



2016-6-6 04:24:10
Use props
rodger
Captain
Flight distance : 411485
  • >>>
United States
Offline

Tom is the man
2016-6-6 04:30:10
Use props
Airspace Explor
Student Pilot
United States
Offline

rodger Posted at 2016-6-6 05:24
Maybe this will help? In electronics and many other types of equipment the term "Cold" refers to th ...

More misinformation, my friend.

In calibrating electronic test equipment, you want the electronics to reach a steady state temperature that is close to the temperature in actual use. As you know, when power is applied, the electronics will heat up to above ambient before remaining at thermal equilibrium. This is known as the warm-up period.

DJI advises that IMU calibration be started when the electronics are at ambient temperature - let it sit with battery removed for 30 minutes. Solid advise, but this goes against what we already know about calibration procedures and doesn't satisfy curious minds.

So there's something else going on here of which we are not aware.

Speculation & bad advise are running wild in this forum and will likely continue without further guidance & clarification from DJI.
2016-6-6 06:36:22
Use props
rodger
Captain
Flight distance : 411485
  • >>>
United States
Offline

Airspace Explor Posted at 2016-6-6 10:36
More misinformation, my friend.

In calibrating electronic test equipment, you want the electronics ...

You are stating exactly what I stated in a different way. Warm up period, electronics are excited (charged) and are running at ambient Temp.
2016-6-6 07:13:38
Use props
Airspace Explor
Student Pilot
United States
Offline

rodger Posted at 2016-6-6 08:13
You are stating exactly what I stated in a different way. Warm up period, electronics are excited  ...

Ambient refers to the temperature outside the shell. When power is applied, the temperature of the electronics will rise above ambient to a steady operating temperature once thermal equilibrium is reached.

The cool down period ensures the temperature of the enclosed electronics is at or below this operating temperature. Otherwise, it will not be at thermal equilibrium during calibration.
2016-6-6 10:00:36
Use props
rodger
Captain
Flight distance : 411485
  • >>>
United States
Offline

Airspace Explor Posted at 2016-6-6 14:00
Ambient refers to the temperature outside the shell. When power is applied, the temperature of the ...

Look, I am trying to explain this so the Gentleman can grasp it. Some of you have him thinking that he has to put his Phantom in the Freezer. Let it sit mr. Explorer. The poor guy is confused. The way that I put it is so he can grasp the meaning of the term cold electronics.
2016-6-6 11:19:46
Use props
Airspace Explor
Student Pilot
United States
Offline

rodger Posted at 2016-6-6 12:19
Look, I am trying to explain this so the Gentleman can grasp it. Some of you have him thinking tha ...

I'll wait for the OP to say if the question has been explained satisfactorily.
2016-6-6 11:48:29
Use props
rodger
Captain
Flight distance : 411485
  • >>>
United States
Offline

Airspace Explor Posted at 2016-6-6 15:48
I'll wait for the OP to say if the question has been explained satisfactorily.

Thank you Sir
2016-6-6 12:20:07
Use props
DJI-Ken
DJI team
Flight distance : 444792
United States
Offline

rodger Posted at 2016-6-7 03:19
Look, I am trying to explain this so the Gentleman can grasp it. Some of you have him thinking tha ...

Actually doing a cold IMU calibration will make the "IMU Warming Up" much faster so that's what I do.
This is a personal preference. I still get the exact same altitudes at known heights if I do a cold calibration or a ambient air calibration.
2016-6-6 12:58:58
Use props
Airspace Explor
Student Pilot
United States
Offline

DJI-Ken Posted at 2016-6-6 13:58
Actually doing a cold IMU calibration will make the "IMU Warming Up" much faster so that's what I  ...

Can you quantify the term 'cold'?
2016-6-6 13:03:55
Use props
DJI-Ken
DJI team
Flight distance : 444792
United States
Offline

Airspace Explor Posted at 2016-6-7 05:03
Can you quantify the term 'cold'?

Out in the garage for 15 minutes on a cold night
2016-6-6 13:10:57
Use props
rodger
Captain
Flight distance : 411485
  • >>>
United States
Offline

DJI-Ken Posted at 2016-6-6 16:58
Actually doing a cold IMU calibration will make the "IMU Warming Up" much faster so that's what I  ...

Thanks Ken, that is what I am trying to tell the Gentleman. He is hearing "Cold" and trying to make a relationship. When we say cold we mean that our Phantom has not been running so that the internal calibration is coming up to speed quicker when we first fire up the Phantom. Thanks for your input.
2016-6-6 16:33:25
Use props
dobmatt
Second Officer
Offline

I'm resting my case ... If I'll go any further with these speculations I'll start banging my head against the brick wall ... Sorry, guys, I know you're trying to help with best intentions, and thank you for all failed efforts ...
2016-6-6 16:58:18
Use props
DJI-Ken
DJI team
Flight distance : 444792
Offline

rodger Posted at 2016-6-7 08:33
Thanks Ken, that is what I am trying to tell the Gentleman. He is hearing "Cold" and trying to mak ...

Actually when I say cold I mean "COLD"
This is not DJI talking but me as a DJI owner for many years. When I do a cold calibration I do it COLD. I lived in the desert and a garage was 110 degrees. So yes, my cold calibration consisted of putting the aircraft (less battery) is a cold environment for 10-15 minutes.
I've done it this way for few years and have never had an issue.
2016-6-6 20:42:33
Use props
RichJ53
Captain
Flight distance : 218508
  • >>>
United States
Offline

rodger Posted at 2016-6-6 17:33
Thanks Ken, that is what I am trying to tell the Gentleman. He is hearing "Cold" and trying to mak ...

rodger

I have followed Kens technique however, I used the refrigerator for about 10-15 mins instead of the cold garage. I do not put the battery inside the refrigerator. First I let the aircraft stabilize for a few minutes while getting the remote and the DJI Go app turned on and ready. Once I turn on the aircraft when it is on the level surface etc. I immediately start the IMU calibration.  (Nascar pitstop speed)

I have had great results using this method on all of my DJI aircraft.  

Rich
2016-6-13 09:05:43
Use props
RichJ53
Captain
Flight distance : 218508
  • >>>
United States
Offline

DJI-Ken Posted at 2016-6-6 21:42
Actually when I say cold I mean "COLD"
This is not DJI talking but my as a DJI owner for many year ...

Agree! I have not had any trouble since using this method Ken


Rich
2016-6-13 09:07:04
Use props
DJI-Ken
DJI team
Flight distance : 444792
United States
Offline

RichJ53 Posted at 2016-6-14 01:07
Agree! I have not had any trouble since using this method Ken

I have never had a single issue when doing this.
A friend said he heard that the altitude would be incorrect from a cold calibration..
I did a room temp IMU calibration and a cold IMU calibration and flew at various known exact heights and both calibrations saw the exact same altitude.
2016-6-13 09:15:45
Use props
RichJ53
Captain
Flight distance : 218508
  • >>>
United States
Offline

DJI-Ken Posted at 2016-6-13 10:15
I have never had a single issue when doing this.
A friend said he heard that the altitude would be ...

Just updated to the latest firmware for the Inspire 1 and no problems. I did a new IMU cal this morning and test flew a few hours ago.  no problems worked great


Rich
2016-6-13 13:46:05
Use props
DJI-Ken
DJI team
Flight distance : 444792
United States
Offline

RichJ53 Posted at 2016-6-14 05:46
Just updated to the latest firmware for the Inspire 1 and no problems. I did a new IMU cal this mo ...

Awesome, thank for reporting Rich.
I'm still waiting for Coach Mode details.
2016-6-13 13:48:27
Use props
RichJ53
Captain
Flight distance : 218508
  • >>>
United States
Offline

DJI-Ken Posted at 2016-6-13 14:48
Awesome, thank for reporting Rich.
I'm still waiting for Coach Mode details.

IMG_0185.PNG

Okay Ken, no problem

see the aircraft has not updated yet

Rich
2016-6-13 13:57:54
Use props
DJI-Ken
DJI team
Flight distance : 444792
Offline

RichJ53 Posted at 2016-6-14 05:57
Okay Ken, no problem

see the aircraft has not updated yet

If you installed the 1.9 update then it is updated (verified by the results TXT file).
It may take a bit for the 1.9 to show up depending o DJI's servers.
2016-6-13 17:16:10
Use props
Rain1dog
Student Pilot
United States
Offline

On my phantom 3... I wrapped my P3 Advanced in a garbage bag and squeezed out as much air as possible and zip tided the opening.  I placed it in the frig for 15 mins and removed from the frig and instantly did a IMU cal.

Reason doing so I was having 1-2 min warm up times.  I read that the IMU stores the temp at which it was cali last and has to warm up to that temp before able to fly.  So you want to cali your quad at temp that is lower than the ambient temp of your location.

Once I did that... As soon as I turn on my P3 A it's ready to fly.... Only time I wait is for the GPS.

Warming up IMU is a thing of the past.  I wrapped it in a bag before placing in fridge to min any moisture related issues.

This has worked perfectly for me... If anyone decides to try this... Please find a reputable tech site that has proper way of doing it, but more importantly explains the reasoning behind it so you know why.
2016-6-13 18:02:54
Use props
Airspace Explor
Student Pilot
United States
Offline

I read that the IMU stores the time at which it was cali last and has to warm up after that time before able to fly. So you want to cali your quad at a time that is before the time of your next flight.

I wear the same shirt I use to cali when I fly and this works perfectly for me.
2016-6-13 18:50:25
Use props
RichJ53
Captain
Flight distance : 218508
  • >>>
United States
Offline

DJI-Ken Posted at 2016-6-13 18:16
If you installed the 1.9 update then it is updated (verified by the results TXT file).
It may take ...

Hi Ken,

I am not worried the txt file confirmed the update and the AC flew just fine...

Rich
2016-6-13 20:42:04
Use props
RichJ53
Captain
Flight distance : 218508
  • >>>
United States
Offline

Rain1dog Posted at 2016-6-13 19:02
On my phantom 3... I wrapped my P3 Advanced in a garbage bag and squeezed out as much air as possibl ...

Agree, thanks for sharing your experience too.

I did not use a bag and this cured my P3P of long warm-up times too. Ken gave me the tip and have been using this ever since on all of the aircraft.

Just wait for GPS (not long)  and ready to go!

Rich
2016-6-13 20:46:24
Use props
DJI-Ken
DJI team
Flight distance : 444792
Offline

RichJ53 Posted at 2016-6-14 12:42
Hi Ken,

I am not worried the txt file confirmed the update and the AC flew just fine...

I updated the P3P, Inspire, and M600 and they all have a +, not to worry
2016-6-13 20:49:50
Use props
RichJ53
Captain
Flight distance : 218508
  • >>>
United States
Offline

DJI-Ken Posted at 2016-6-13 21:49
I updated the P3P, Inspire, and M600 and they all have a +, not to worry

Ken,

I updated the P3P... my Inspire 1 V2  but I have not touched the back up Inspire 1 V2 yet    I could not really see anything different on the map in my area..

Rich
2016-6-13 21:12:48
Use props
rodger
Captain
Flight distance : 411485
  • >>>
United States
Offline

RichJ53 Posted at 2016-6-13 13:05
rodger

I have followed Kens technique however, I used the refrigerator for about 10-15 mins inste ...

Glad you are satisfied. whatever works for you. I still do it with the ambient temp. I want everything to be calibrated in the environment that I am flying in. Warm up is only a matter of seconds. Good to see that you are on a flat level surface, that is most important.
2016-6-14 02:13:30
Use props
DJI-Ken
DJI team
Flight distance : 444792
United States
Offline

RichJ53 Posted at 2016-6-14 13:12
Ken,

I updated the P3P... my Inspire 1 V2  but I have not touched the back up Inspire 1 V2 yet  : ...

Some map data may have changed in some areas and some not.
2016-6-14 06:22:57
Use props
laser132
Beginner
Flight distance : 11891
United Kingdom
Offline

Hey Tom have you had a chance to calibrate the transmitter yet, and if you have, have you made a video of you doing it?
Cheers.
Bill (laser132)
2016-6-22 02:31:00
Use props
DJI-Paladin
DJI team
Hong Kong
Offline

laser132 Posted at 2016-6-22 18:31
Hey Tom have you had a chance to calibrate the transmitter yet, and if you have, have you made a vid ...

You can follow this video to calibrate your RC:
2016-6-22 02:32:53
Use props
HarborHouseLife
Beginner
Flight distance : 101409
United States
Offline

How do I calibrate phantom 4 on boat?  On the rocking boat, it keep calibrating IMU, if not pass it wouldn't let me take off. Do you know how to skip process  
2016-7-26 13:39:03
Use props
DJI-Paladin
DJI team
Hong Kong
Offline

HarborHouseLife Posted at 2016-7-27 05:39
How do I calibrate phantom 4 on boat?  On the rocking boat, it keep calibrating IMU, if not pass it  ...

If it tells you to calibrate the IMU and doesn't let you take off, it is necessary to calibrate the IMU again.I'd suggest you to calibrate it on land before if the boat is rocking.
2016-7-26 19:55:39
Use props
fans4861cfa3
Hobbyist
Flight distance : 274857
  • >>>
France
Offline

its not the same process now for Phantom 4 pro and need to move uav P4P so for me tjhis video is too old !!
2016-12-6 03:34:37
Use props
krakmh
Beginner
Pakistan
Offline

i am stuck on 1/6, Any solution? Tried resetting RC and Plan but no luck.
2017-6-11 18:37:47
Use props
Ryan L GNC
Beginner
United States
Offline

All - It seems like there was a whole lot of confusion about the whole question of why a warming up process. My guess (I don't work at DJI) has to do with some of the fundamental workings of IMUs. A brief explanation/my thoughts (not to beat a dead horse or anything):

An IMU consists mainly of two parts: (1) accelerometers (tells you about how you're moving translationally through space), and (2) gyroscopes (tells you about how fast you're rotating). These sensors are physically imperfect and so there are errors associated with them (random walk, scale factors, misalignments, and biases). All of these errors, if not known and accounted for, are integrated (added up) over time and can produce really poor performance. Because of the way that these sensors are physically made, the sensors' temperature has an effect on how accurate the sensors are. I suspect that the warm up process is built into the calibration routine to help better estimate what all the scale factors, misalignments, and biases are as they rise to operating temperature so their effects can be effectively minimized during flight.

Hopefully that explanation better helps to understand the underlying issues and satisfies some curiosity.

As far as the whole sticking it in a freezer with or without a bag, I'd simply recommend being really careful - especially if you live in a humid place. The danger is from condensation collecting on the internal electronics. Water and electrical boards have not historically gotten along well excepting specific, intentional applications. ;)

-Ryan
2017-7-6 10:29:02
Use props
Aardvark
Captain
Flight distance : 76452
United Kingdom
Offline

The latest firmware etc may be a game changer for IMU warmup period. I had previously calibrated IMU on a cool night last winter, about 5 degrees C. Since then I had not calibrated the IMU, and it always started up fairly quickly. With all todays updates for the P4 I decided to do all calibrations. Forgetting of course about cool IMU etc, or even a cool down period to be honest. So I completed new (for P4) IMU calibration routine at an ambient air temperature of about 20 C. The aircraft starts up and the IMU warmup lasted but a few seconds, very similar to previous time I would say.
2017-7-6 11:42:46
Use props
fester
Hobbyist
Flight distance : 15503
United States
Offline

Aardvark Posted at 2017-7-6 11:42
The latest firmware etc may be a game changer for IMU warmup period. I had previously calibrated IMU on a cool night last winter, about 5 degrees C. Since then I had not calibrated the IMU, and it always started up fairly quickly. With all todays updates for the P4 I decided to do all calibrations. Forgetting of course about cool IMU etc, or even a cool down period to be honest. So I completed new (for P4) IMU calibration routine at an ambient air temperature of about 20 C. The aircraft starts up and the IMU warmup lasted but a few seconds, very similar to previous time I would say.

   The new IMU cal procedure is probably much more precise, but its a considerable change from the previous P4 cal.
2017-7-6 16:37:20
Use props
12Next >
You need to log in before you can reply Login | Register now

Credit Rules

Close

DJI RecommendsPrevious /1 Next