New Phantom 4 after even exchanged at the Apple Store update!!

[Stealthmatt]

I'm sorry, I have to agree here. Sure there is expansion, nominal but it's there. However, it's not noted by DJI anywhere, and also, what about all of us, (I for one) who think it's silly to put my craft in a refer to calibrate it, but have a perfectly flying bird. I LIKE Matts comments and think he adds plenty to discussions, but on this, not even him now, I think some ppl take it way way overboard. If you really want your **** to work right, follow these guys from AutoFlightLogic and Litchi who state categorically DO NOT COLD TRICK the IMU calibration.

These are expensive machines/computers and do what gives you the "warm and fuzzy". But I would state this, in my reading and understanding these two things are prolly your best bet; first turn the bird on 5 minutes before you calibrate to let all internals get to operating temp. Before you fly, let the bird properly warm up, if this means turning it on a few minutes before flight, then so be it, it may, may cost you a few seconds of flight time, but to be honest, what's a stabile bird worth to you? If your willing to through it in a refrigerator! You should be willing to let it warm up for a couple minutes.

Here's another valid point, going from extremes, like the guys bringing their crap out of a cold cold environment, then heating up to operational temps, IS SUPER HARD ON SOLID STATE BOARDS! THIS IS WAY WAY WORSE THEN LEAVING YOUR STUFF ON ALL THE TIME, and in fact, (look it up) engineers will tell you as far as computers and stuff like this goes, your doing most of the wear and tear on machines when putting them through this heat cycle, leading to brittle hardware and degraded connections, NO WAY would I freeze my bird then turn it on, especially over time, dollars to donuts this will lead to a premature failure. Take what you will of my $.02 but I doubt 30 years of experience is steering me in the wrong direction here. If there was an issue in the past, well I get that, but your asking for trouble in a P4 with this idea.


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Yeah, I don't like the idea of putting it in the fridge. Cooling it down to around 15c is the lowest I would go and using air conditioner not the fridge.

It's hard to say what is right way and wrong way. All DJI reps have stated to do cold IMU calibrations, but third party SDK vendors that don't work for DJI have apparently (and I say apparently because I have not see any statement from them other than people saying they have) not to do cold or it doesn't matter.

So do you believe the official representation of DJI, or do you believe the SDK builders?

 

[Sim597]

Im

Could you post the links to the statements by Litchi and Autlight Logic? I haven't seen them before.

im not that good at this, but yeah, I'll look around, I think I just read one, gimme a few....

 

[Sim597]

Yeah, I don't like the idea of putting it in the fridge. Cooling it down to around 15c is the lowest I would go and using air conditioner not the fridge.

It's hard to say what is right way and wrong way. All DJI reps have stated to do cold IMU calibrations, but third party SDK vendors that don't work for DJI have apparently (and I say apparently because I have not see any statement from them other than people saying they have) not to do cold or it doesn't matter.

So do you believe the official representation of DJI, or do you believe the SDK builders?

Oh, we'll see I haven't seen or hear DJI say anything, nothing written anyway, but I remember the post and the couple guys u mentioned, I'm going to assume they're reps, i didn't know

 

[Stealthmatt]

Oh, we'll see I haven't seen or hear DJI say anything, nothing written anyway, but I remember the post and the couple guys u mentioned, I'm going to assume they're reps, i didn't know

I have just asked the question in rcgroups

This is from offical DJI rep

actually the cold IMU is new from the Inspire 1 on. I was the one the actually found out how a cold calibration does effect this FC while beta testing the i1. It helps with the warm ups and provides much better calibration data through a wider range of temps. It can help the gimbal as well since the gimbal also talks with the main IMU.

The autoquad 6 FC does kind of the same thing with it's calibration base, it takes hours though.

RC Groups - View Single Post - Official Phantom 4 ***Owner's Thread***

From another user:

The IMU is heated, the second you turn the craft on it begins to warm up, when you perform a calibration from say room temp the IMU is constantly getting warmer and warmer till it reaches its normal operating temperature , this is taken from ambient onwards so this range is fairly small.

Now when you take your craft out into the field thats much colder the Initial aircraft warmup will wait for the IMU to reach temperature, this could take a few minutes because your IMU is now having to work from much colder and the calibrated temp is much higher so it has to wait to warm up, this can also have an affect on IMU accuracy and has been shown to cause issues with the gimbal especially.

By cooling your craft first before you calibrate the IMU your letting git calibrate over a much wider temperature range, this means in the field it does not have to warm up as far giving you much faster warmup times, secondly as the IMU has been calibrated over a far wider temperate range its accuracy should be more stable.

RC Groups - View Single Post - Official Phantom 4 ***Owner's Thread***

 

[Sim597]

Aircraft height (altimeter) may easily vary 15-20m (50-66ft) off the actual height after aircraft flying and heating up several minutes. You are recommended to let IMU warn up properly on the ground especially in cold weather, and set waypoint height minimum 25m (82ft) above any obstacles. Cold IMU calibration trick is NOT recommended which might incur more discrepancy in altimeter reading.



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[Sim597]

^^ that was about litchi in the FPV camera app, I know I've seen it in other places


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[Stealthmatt]

Aircraft height (altimeter) may easily vary 15-20m (50-66ft) off the actual height after aircraft flying and heating up several minutes. You are recommended to let IMU warn up properly on the ground especially in cold weather, and set waypoint height minimum 25m (82ft) above any obstacles. Cold IMU calibration trick is NOT recommended which might incur more discrepancy in altimeter reading.



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sorry where are you quoting this from?

 

[Sim597]

Could you post the links to the statements by Litchi and Autlight Logic? I haven't seen them before.

Aircraft height (altimeter) may easily vary 15-20m (50-66ft) off the actual height after aircraft flying and heating up several minutes. You are recommended to let IMU warn up properly on the ground especially in cold weather, and set waypoint height minimum 25m (82ft) above any obstacles. Cold IMU calibration trick is NOT recommended which might incur more discrepancy in altimeter reading.
Here's what I found, when I come across more I'll post them. This is the most detailed I've seen anyone post any data, this was about the litchi app I believe, in FPV camera app, I'll look for the other stuff though


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[Sim597]

Hmm, how do I post a pic... In this app, hang on, I'll post the address


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[Sim597]

Important Notes


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[Sim597]

Look at that one...I could swear I read it differently so I think it's in other places, I warned u guys I'm not that good at finding old stuff I've read, I read ALOT (by definition then, some has to be crap right!? ) Lol


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[Sim597]

I think I am wrong it being ABOUT Litchi, sorry

This instruction thing anyway, I thought it was like a VR app talking about Litchi, again, I read a lot so, it's easy to get confused on what and where I am, I've read the Litchi help, and the huge detailed involved AutoFlightLogic flight school, just in the last 2-4 days, on top of all the other crap
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[Sim597]

sorry where are you quoting this from?

You realize I hope that I'm not arguing with you right? I mean, like I said, I don't like the idea of chilling IC boards and heating them, that is a huge no-no if you can help it, and certainly can lead to problems when done a few times, I firmly believe that. But I do get it if it was some kind of "fix" back in the day or something and ppl had luck with it, even though data proving that is surely inconclusive, as we talked before, some guys have never done it and had no problems.
So getting info and hashing it out seems like the right thing to do that's all. And then I remembered reading about it, more then once, but I can't seem to locate that, it just seems only fair if I read it to share it, that is about the P4 too as u noticed so the inspire trick could be a thing guys believe in and swear on, I'm dubious, but that's me being a mechanical systems installer for 30+ years, specializing in heating and cooling actually


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[Stealthmatt]

You realize I hope that I'm not arguing with you right? I mean, like I said, I don't like the idea of chilling IC boards and heating them, that is a huge no-no if you can help it, and certainly can lead to problems when done a few times, I firmly believe that. But I do get it if it was some kind of "fix" back in the day or something and ppl had luck with it, even though data proving that is surely inconclusive, as we talked before, some guys have never done it and had no problems.
So getting info and hashing it out seems like the right thing to do that's all. And then I remembered reading about it, more then once, but I can't seem to locate that, it just seems only fair if I read it to share it, that is about the P4 too as u noticed so the inspire trick could be a thing guys believe in and swear on, I'm dubious, but that's me being a mechanical systems installer for 30+ years, specializing in heating and cooling actually


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Oh yeah man, I know your not arguing, I am trying to understand it for myself so I can make the best decision. If we go in life accepting everything at face value we would never grow.

How much temprature range can effect IC boards, if we say go from 18c to 30c in a time frame of 2 minutes - is that too much of a temp range for IC boards?

Apprently the Inspire 1 had a heater in it to heat up the IMU.

RC Groups - View Single Post - Official Phantom 4 ***Owner's Thread***

 

[Sim597]

Oh, well look, you have to remember that like all things, some are made more durable then others. So the thing with this board, is its NoT made for extreme temp variations, I will say by looking at what I saw in the 3, and some pics of the 4 these appear to me to be pretty well made, IC boards are not my specialty at all, buildings and processing were what I did, so I'm sure in here someone will know more. (There's always a guy or three that know more right? Lol it's just DO they really, a guy like u or me can usually tell by the content in which they speak) so, dang 18 to 30c I don't think that's too big of a difference, and in THAT is the big thing, the separation between the hot and cold, if your asking if Inthink you've done damage, I doubt it at that temp range. Keep in mind, I'm in the US (don't hate me, Trump is an idiot, I also hated bush before it was cool, and was against Iraq from DaY one, we aren't all mouth breathers like you see behind Ted Cruz, who's a Canadian btw!)
So I work in F* but 12c isn't more then like 35-40F right? So, ok you've made me think about this for the first time, as some had said freezer? I was thinking colder then say, a fridge with milk should be about 40-42f? And then heating up the bird would make the board hum at what, 120F so that's about maybe 80*F difference, that more the 12*C right?


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[Sim597]

This is all speculation I don't know what these run at, but I can dig out my temp gun or FLiR cam and find out


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[Stealthmatt]

I used my temp gun before it was 18c (64.4F) after calibration it was 30c+ (86F) inside the shell.

I would not recommend in the freezer or fridge, condensation which in turn water and electronics don't mix. also rapid temperature change creates condensation.

I calibrated in the same room as the aircon.

The phantom 4 heats up pretty fast.

 

[GadgetGuy]

Basically, the IMU needs more temperature range to get the best level. As it gets hotter metals in the IMU expand and it doesn't give a good range to calibrate.

The Phantom gets pretty hot fast i.e 30 degrees in the core, this is not good for calibration. So the colder the better. Some people leave it in the garage over night to cool right down.

With all due respect, the only reason for a cold IMU calibration is to reduce start up time, as the IMU has to first heat up to the same temperature it was calibrated at. It just takes longer to be able to fly, wasting valuable battery life on the ground waiting to fly. The calibration is otherwise unaffected by normal temperature ranges. If you need a super accurate barometer reading, then warm up the bird in a hover, land, replace the battery, and go. Nothing requires that you take off as soon as the IMU is at the calibration temperature, but you cannot take off until it reaches that temperature. A warm 80°F IMU calibration may take 5 minutes to be able to fly every time. Calibrating the IMU cold after leaving it in front of an AC unit for 10 minutes with the battery removed, while also cooling the battery in the same cool air, can reduce that start up time to a mere 30 seconds, saving 4.5 minutes waiting. Do as you like, but cool calibrations make for faster deployment "when the moment is right!"

 

[yorlik]

This is all speculation I don't know what these run at, but I can dig out my temp gun or FLiR cam and find out

With all you are suggesting, THIS sounds like a good idea for you before you continue posting such.

Hot to cold IMU calibration will change your altitude 50-60 feet???? Huh? You DO realize that IMU has NOTHING to do with altitude measurement, right??? There is that little itty bitty sensor called a barometric pressure sensor mounted in one of your landing legs.... IT tells altitude - not IMU....

Don't freeze your IMU to calibrate and make it wrong as a result of OLD P2 design flaw.....

 

[Stealthmatt]

With all you are suggesting, THIS sounds like a good idea for you before you continue posting such.

Hot to cold IMU calibration will change your altitude 50-60 feet???? Huh? You DO realize that IMU has NOTHING to do with altitude measurement, right??? There is that little itty bitty sensor called a barometric pressure sensor mounted in one of your landing legs.... IT tells altitude - not IMU....

Don't freeze your IMU to calibrate and make it wrong as a result of OLD P2 design flaw.....

No, your facts are incorrect the compass is in the legs.

Research what an imu is.... Inertial measurement unit - Wikipedia, the free encyclopedia

Love it when people start making stuff up to make their point.