Welcome to PhantomPilots.com

Sign up for a weekly email of the latest drone news & information

Cold IMU calibration thoughts

Discussion in 'Standard/4k Discussion' started by Pharm, Aug 27, 2016.

  1. Pharm

    Joined:
    Jun 14, 2016
    Messages:
    730
    Likes Received:
    260
    I hear a lot of people recommending putting the bird in the refrigerator for 30 minutes or so before doing an IMU cal. This seems a bit risky. Upon removing it from the refrigerator, if there's any humidity, water is going to condense on it AND INSIDE it fairly quickly. Then you're calibrating a potentially wet electrical system. This doesn't seem like a good idea to me. Thoughts?
     
    #1 Pharm, Aug 27, 2016
    Last edited: Aug 28, 2016
  2. dirkclod

    dirkclod Moderator
    Staff Member

    Joined:
    May 9, 2014
    Messages:
    10,648
    Likes Received:
    5,702
    Location:
    Amory Mississippi
    I sit mine in front of an AC vent so the cool air goes in the battery box for about 30 minutes and that works good for me here in my climate .
     
    RodPad likes this.
  3. With The Birds

    Joined:
    Jan 4, 2016
    Messages:
    2,608
    Likes Received:
    742
    Location:
    Australia
    I stopped the fresh out of fridge routine when i was having significant alt reading accuracy issues. Havent had them since.
     
  4. Multicoptertec

    Joined:
    Mar 4, 2016
    Messages:
    1,091
    Likes Received:
    313
    Location:
    Apollo Beach, Florida
    I don't think the Phantom was ever designed to be refrigerated. Don't see it anywhere in the manual either. BUT, I have no data to prove or disprove this. AND, my P3A always takes a while to warm up, and while others are already airborne, I am staring at the message, "Aircraft warming up", which is somewhat confusing, because it's usually 90F when we fly. SO, in another hopeful attempt at mitigating this issue, I just did an(other) IMU cal within seconds of powering on the P3A in a 73F room. Flying tomorrow morning, pending any tropical disturbances from Invest 99L.


    Sent from my iPad using PhantomPilots
     
  5. RodPad

    Joined:
    May 20, 2015
    Messages:
    2,641
    Likes Received:
    367
    Location:
    Pacific,NorthWet, 97031
    "I don't think the Phantom was ever designed to be refrigerated" :D
    That's really funny!

    I don't have any problem waiting for the warming up message to stop, gives me some mental time to think of other things before I take off.

    Refrigeration is going to add moisture, do you want your fruits and vegetables dry or most?

    @With The Birds said, "fresh out of fridge" :D
    That was good also!

    So since AC actually is actually the removal of moister and a refrigeration process.
    Refrigeration is actually not cooling but process of removing heat.


    @dirkclod has my vote for the best IMU calibration concept, still close to normal outside temps. but not the funniest.;)

    Rod
     
  6. GMack

    Joined:
    Jul 26, 2016
    Messages:
    562
    Likes Received:
    146
    I've often wondered about this "It must be cold for an IMU calibration" idea. It may be some old tale that has taken hold over time.

    Most all test equipment I've worked with such as oscilliscopes, smog testing equipment, expensive Eizo color monitors, etc. stipulate a warm-up period for best performance prior to actual use. Even the Phantom has a warm up period. Actually, one of my Nikon cameras seems to have a warm up period in that the auto-focus seems to work better after a few shots and the light metering seems to zero in better with a bit of 'ON' time.

    I'd guess that any normal ambient temp near the 1-2 minute P3/P4 warm up is good enough. Any thermal drift from being too cold (refrigerated, etc.) may be detrimental to the final calibration since the drone seems to need a settling in period and hardware warming during starting it up.
     
  7. dirkclod

    dirkclod Moderator
    Staff Member

    Joined:
    May 9, 2014
    Messages:
    10,648
    Likes Received:
    5,702
    Location:
    Amory Mississippi
    No it does not have to be cold but it does take away the warm up time .
    If you will look back and search for the threads on all the time that the members here
    researched and tested this before you joined you will see .
    I do them and in my climate as soon as I power up I am ready to go .
    When I see it has to warm up when I power it up I just do another cold IMU Cal
    and all is good .
     
  8. MikeB2308

    Joined:
    Feb 17, 2016
    Messages:
    12
    Likes Received:
    7
    Put my Phantom in the refrigerator for 20 minutes yesterday after having about a 1-2 minute "warm-up" time....Worked perfectly...Just make sure the room you calibrate it in is not humid and do it immediately...Take battery out while in fridge....
    Might as well calibrate gimbal after imu.....
    Also, probably most important, make sure surface is as level as possible....
     
  9. Dirty Bird

    Joined:
    Apr 15, 2014
    Messages:
    0
    Likes Received:
    9
    Location:
    Glen Burnie, MD - USA
    As has been mentioned earlier, what the cold IMU calibration does is reduce the bird's warm-up time. My P4 initially took nearly a minute to warm up. After the cold IMU calibration it warms up within only a few seconds.
     
  10. Lennart wiklund

    Joined:
    Sep 4, 2016
    Messages:
    15
    Likes Received:
    1
    Location:
    Sweden,north part. Jämtland(county)
    Hi folks! I did do a cold calibration now today,its plus 3degrees here in Sweden today. I put the bird outside for about 50 minutes. Had everything clear in screen on my iPad. Now it well be ready to fly in about 10 seconds max. It's a P3 Advance
     
    #10 Lennart wiklund, Oct 8, 2016
    Last edited: Oct 8, 2016
  11. Lennart wiklund

    Joined:
    Sep 4, 2016
    Messages:
    15
    Likes Received:
    1
    Location:
    Sweden,north part. Jämtland(county)
    Just been out now for two testflights,and its warming upp just in a few seconds,it take longer time to find the satelites and green screen