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IMU Calibration
4188 27 2017-2-18
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Will.H
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United Kingdom
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Hi,

Sorry for the (possibly stupid) question.

Can the IMU calibration be completed indoors? Not very technical I'm afraid...

Thanks

Will
2017-2-18
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fans06b77ccc
lvl.4
Flight distance : 1905381 ft
United States
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Sure can! The important thing while following the orientation shown in picture is to make sure to do it on a level surface. Confirm this by using a bubble level. Also best to make sure the AC is cold prior to starting the IMU. My understanding is this is to minimize the IMU start time when first turning in the AC.
2017-2-18
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fans06b77ccc
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Sure can! The important thing while following the orientation shown in the picture directions is to make sure to do it on a level surface. Confirm this by using a bubble level. Also best to make sure the AC is cold prior to starting the IMU. My understanding is this is to minimize the IMU start time when first turning in the AC. You should however perform the compass calibration outside away from any magnetic interference .
2017-2-18
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Will.H
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United Kingdom
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Thanks! I was just going to do it on the floor at home? I hope that's level!
2017-2-18
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fans06b77ccc
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Will.H Posted at 2017-2-18 05:39
Thanks! I was just going to do it on the floor at home? I hope that's level!

Best to check. I would have assumed that but not always true, especially in older homes. Even it being a small amount, undetectable to the eye, can make a difference in properly calibration of the IMU.
2017-2-18
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fans06b77ccc
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Will.H Posted at 2017-2-18 05:39
Thanks! I was just going to do it on the floor at home? I hope that's level!

I would have assumed home floors were level, but not always true in older homes. The level can make a big difference in correctly calibrating IMU.
2017-2-18
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Will.H
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United Kingdom
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Does it take long? I know it says 5 minutes, but mines been stuck at 95% for about that long now. Not sure if it's frozen...?
2017-2-18
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dronist
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Will.H Posted at 2017-2-18 06:17
Does it take long? I know it says 5 minutes, but mines been stuck at 95% for about that long now. Not sure if it's frozen...?

Then you did not follow up correctly on one of the images.

Best to do is a COLD IMU calibration. Take battery and props off, leave it outside for at least 1/2 hour have your remote on and ready and bring AC back in, put the battery in and start the calibration. Need to follow the screen EXACTLY. Again if it got stuck it means it is waiting for the correct position of the AC.

After that do shut everything off and then do an AUTOMATIC Gimbal calibration.
2017-2-18
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DroneFlying
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Will.H Posted at 2017-2-18 06:17
Does it take long? I know it says 5 minutes, but mines been stuck at 95% for about that long now. Not sure if it's frozen...?

No, it really should only take a few minutes. And as dronist said, it's best to do it when the aircraft has been cooled ("cold" in this case literally meaning temperature-wise) by leaving it for 30 minutes or so in the refrigerator -- or outdoors if the temperatures are accomodating.
2017-2-18
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Heavysledz
Second Officer
Flight distance : 819491 ft
United States
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can someone elaborate on why you ned to cool the Mavic before doing an IMU calibration?
2017-2-18
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DroneFlying
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Heavysledz Posted at 2017-2-18 10:34
can someone elaborate on why you ned to cool the Mavic before doing an IMU calibration?

It's not really required but can make the aircraft ready to fly faster after it's powered on than if you calibrated it at room temperature.
2017-2-18
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Anoniem
First Officer
Flight distance : 70043 ft
Netherlands
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My explanation as I understand(by reading from others):
Doing a IMU calibration, it senses the temperature at that moment. If your mavis has been on for a while it will be warmed up, this temperature is been saved to the drone doing the IMU procedure.
So if you go out to fly and power up, the startup procedure will take longer until the saved temperature is the same as the one that at the time you did the IMU procedure.
You can try out for yourself of course
2017-2-18
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hallmark007
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DroneFlying Posted at 2017-2-18 10:25
No, it really should only take a few minutes. And as dronist said, it's best to do it when the aircraft has been cooled ("cold" in this case literally meaning temperature-wise) by leaving it for 30 minutes or so in the refrigerator -- or outdoors if the temperatures are accomodating.

Not really a good idea to put electronics in a refrigerator, maybe inside a sealed bag . But why would you risk it.
2017-2-18
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Will.H
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dronist Posted at 2017-2-18 09:47
Then you did not follow up correctly on one of the images.

Best to do is a COLD IMU calibration. Take battery and props off, leave it outside for at least 1/2 hour have your remote on and ready and bring AC back in, put the battery in and start the calibration. Need to follow the screen EXACTLY. Again if it got stuck it means it is waiting for the correct position of the AC.

Hi, the images didn't come up. It had 2 bars, and the second starting going up. It stopped at 95%. In the end I switched both off and started again. This time the images came up and I completed it as directed.

Flown it 3 times today and works like a dream. Amazing machine.
2017-2-18
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Anoniem
First Officer
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hallmark007 Posted at 2017-2-18 13:16
Not really a good idea to put electronics in a refrigerator, maybe inside a sealed bag . But why would you risk it.

Hi Hallmark007, can you tell me why you do not think this is very wise to do.. putting it in a fridge(+7 degree Celsius)?
What is the difference to putting it outside(dry).. the difference in temperature is the same, what could happen that you do not want to happen?
2017-2-18
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hallmark007
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Anoniem Posted at 2017-2-18 13:52
Hi Hallmark007, can you tell me why you do not think this is very wise to do.. putting it in a fridge(+7 degree Celsius)?
What is the difference to putting it outside(dry).. the difference in temperature is the same, what could happen that you do not want to happen?

There is a lot of humidity moving around a very small area inside your refrigerator, this will not mix very well with electronics, I don't think it's a good idea, an outside garage or cold room is ideal.
2017-2-18
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thehippoz
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United States
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Fridge is ok if you put it in a bag that's sealed from moisture, can speed it up like that just needs around 30 minutes. You want to put it rightside up, then from the back- tip left on it's side, then right. The rest is shown, bottom, upside down. The key to getting a good one is doing it all before the ac fan comes on.

I've 0's to .001 on everything in the IMU sensor page like this after it's warmed up and flown a few, but gyro 2. It's always between .001 and .006 no matter what I do. It's always been like this from the factory. I did get it stuck between .001 and .002 after a recent calibration but it went back after flight. Oh yeah there shouldn't be any vibrations on the surface used.
2017-2-18
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rick39
Second Officer
Flight distance : 164354 ft
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The humidity of a fridge is relatively dry. The problem isn't so much in the fridge, it's when you take it out of the fridge. Introducing anything from a cold environment to a warm one will create condensation. The higher the temperature difference between the two environments the more likely condensation will occur. Ideally you should cool the Mavic outside and calibrate it there too. This saves any risk of condensation and stops the Mavic from warming up again when you bring it inside.
Obviously the difference in temperature has to be quite high for it to be a risk, as well as considering relative humidity differences between the two environments. Think of glasses steaming up when coming from outside on a cold day and back into a nice warm house, or taking a bottle of cold milk out of the fridge and leaving it for a minute or two on a kitchen worktop. This will be more evident with non porous objects and doesn't just affect the outside surface of the object, but anywhere where air is present, which includes the inside of a drone..
2017-2-18
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hallmark007
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rick39 Posted at 2017-2-18 19:16
The humidity of a fridge is relatively dry. The problem isn't so much in the fridge, it's when you take it out of the fridge. Introducing anything from a cold environment to a warm one will create condensation. The higher the temperature difference between the two environments the more likely condensation will occur. Ideally you should cool the Mavic outside and calibrate it there too. This saves any risk of condensation and stops the Mavic from warming up again when you bring it inside.
Obviously the difference in temperature has to be quite high for it to be a risk, as well as considering relative humidity differences between the two environments. Think of glasses steaming up when coming from outside on a cold day and back into a nice warm house, or taking a bottle of cold milk out of the fridge and leaving it for a minute or two on a kitchen worktop. This will be more evident with non porous objects and doesn't just affect the outside surface of the object, but anywhere where air is present, which includes the inside of a drone..


, refrigerator humidity can vary wildly. If left closed for an extended period, it can become rather dry (under 10%)since the air is being forced over a chilled coil causing moisture to condense and drip away. But open the door on a hot summer day and the humidity level will shoot up to near 100% almost instantly as the cool, dry air collides with the warm moinst air. Ever see the fog that rolls out of an open fridge or freezer? That's 100% relative humidity and indoor 'rain'. Remember; it's all "relative".

My advice was not to put Mavic in the refrigerator it's a silly risk to take...
2017-2-18
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rick39
Second Officer
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United Kingdom
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hallmark007 Posted at 2017-2-18 22:39
, refrigerator humidity can vary wildly. If left closed for an extended period, it can become rather dry (under 10%)since the air is being forced over a chilled coil causing moisture to condense and drip away. But open the door on a hot summer day and the humidity level will shoot up to near 100% almost instantly as the cool, dry air collides with the warm moinst air. Ever see the fog that rolls out of an open fridge or freezer? That's 100% relative humidity and indoor 'rain'. Remember; it's all "relative".

My advice was not to put Mavic in the refrigerator it's a silly risk to take...

That's right hallmark, I was trying to explain why it is a bad idea and the reasons for it, namely condensation.
2017-2-19
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Heavysledz
Second Officer
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So if performing the IMU calibration when the Mavic is cold somehow results in speeding up the initial start up before flying, how does it react if the IMU calibration was done at a cold temperature and you are going to fly it in a hotter temperature?
2017-2-20
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hallmark007
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Heavysledz Posted at 2017-2-20 14:12
So if performing the IMU calibration when the Mavic is cold somehow results in speeding up the initial start up before flying, how does it react if the IMU calibration was done at a cold temperature and you are going to fly it in a hotter temperature?

It will just react and start up quicker.
2017-2-20
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DroneFlying
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Heavysledz Posted at 2017-2-20 14:12
So if performing the IMU calibration when the Mavic is cold somehow results in speeding up the initial start up before flying, how does it react if the IMU calibration was done at a cold temperature and you are going to fly it in a hotter temperature?

The IMU will stay in the "initializing" state until it reaches a certain temperature -- and apparently that baseline temperature is determined when you calibrate. So the idea is that if you calibrate when it's at a lower temperature it'll reach the baseline faster when warming up.
2017-2-20
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ClancyO
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This all seems a little crazy to me...I seriously doubt that DJI is popping these out of a fridge before the initial factory IMU calibration.  Now I'm afraid to even try this.
2017-2-20
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DroneFlying
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ClancyO Posted at 2017-2-20 15:55
This all seems a little crazy to me...I seriously doubt that DJI is popping these out of a fridge before the initial factory IMU calibration.  Now I'm afraid to even try this.

This all seems a little crazy to me...I seriously doubt that DJI is popping these out of a fridge before the initial factory IMU calibration

Nobody ever said that DJI uses a refrigerator. Here's what one DJI employee (Natalia) said about it, though:

"A Thermometer detects aircraft temperature and, over time, changes in aircraft temperature. Each time you turn on your drone, the IMU needs to warm up to the temperature at which you last calibrated. For example, if you calibrate the IMU at room temperature, the next time when you start the drone, it needs to warm up to room temperature before its ready to fly. Sometimes pilots get frustrated if their IMU takes too long to warm up. The drone may be taking a while because the IMU was last calibrated at a relatively high temperature. This is why we often recommend calibrating while your drone is cooled down. For example, trying placing it near an AC vent or unit before calibration."
And another:

"The IMU is calibrated at the factory in a controlled environment to allow for quick start up."

So no, not "crazy".
2017-2-20
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Heavysledz
Second Officer
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DroneFlying Posted at 2017-2-20 16:04
This all seems a little crazy to me...I seriously doubt that DJI is popping these out of a fridge before the initial factory IMU calibration

Nobody ever said that DJI uses a refrigerator. Here's what one DJI employee (Natalia) said about it, though:

Thanks for the info......I will give it a try.....I honestly have never performed an IMU calibration after 40 flights and 4 hours of flight time logged. Haven't seen the need to do so and the Mavic fly's great. also, I always let Mavic GPS pick up as many satellites as possible and stabilize before I take off to ensure a better fix on the home position.

But will definitely keep all of this in my back pocket for when I do perform a full IMU calibration.
2017-2-20
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AG0N-Gary
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Not on a Mavic, but my P3, when calibrated at 80 degrees F, takes a little less than three minutes to warm up and be ready to fly.  When calibrated at 16 deg F, takes less than 1 minute.
2017-2-20
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ClancyO
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DroneFlying Posted at 2017-2-20 16:04
This all seems a little crazy to me...I seriously doubt that DJI is popping these out of a fridge before the initial factory IMU calibration

Nobody ever said that DJI uses a refrigerator. Here's what one DJI employee (Natalia) said about it, though:

Thank you for the additional insight.  I will avoid any warm temperatures when I calibrate.  
2017-2-21
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