Welcome to PhantomPilots.com

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

Always calibrate your compass!

Discussion in 'Phantom 2 Discussion' started by tferrari, Aug 18, 2014.

  1. tferrari

    Joined:
    Aug 4, 2014
    Messages:
    145
    Likes Received:
    1
    I finished degaussing my compass (waving magnet over it in multiple planes to remove any residual magnetism) some time yesterday, performed an advanced IMU calibration in the DJI software and headed out the door for a quick test flight.

    I started the unit, got my GPS fix and home position (two sets of green flashing lights) and took off without realizing that I forgot to perform my field calibration of compass (compass dance).

    Luckily my phantom was only about 5 feet off the ground when I realized that all of my directional commands were not translating to any logical response. I checked the course lock button and it was not engaged. By the time I switched to ATTI mode (to counteract the junk compass info being utilized in GPS mode) it was too late and my phantom came down on an angle into the grass in my back yard. Nothing was damaged, but a prompt compass calibration after this solved the issue.

    This is just a reminder of how important that compass calibration really is.. especially after degaussing and an advanced IMU calibration.

    Doh!
     
  2. sijbren

    Joined:
    May 26, 2014
    Messages:
    48
    Likes Received:
    1
    Location:
    The Netherlands
  3. ianwood

    ianwood Taco Wrangler
    Staff Member

    Joined:
    Jan 7, 2014
    Messages:
    4,910
    Likes Received:
    1,789
    Location:
    Lost Angeles
    You don't always want to calibrate your compass.

    DON'T calibrate your compass if:

    • You're in an urban area surrounded by concrete, buildings, and hidden or overhead powerlines/pipes/etc.
    • You're on the beach or on a boat.
    • You're close to large mineral deposits, metallic objects or anything magnetic.

    DO calibrate your compass if:

    • You go to a new location that is a good distance (>25 miles) from the last place you calibrated the compass.
    • You change any equipment on your Phantom.
    • You just installed new firmware.
    • You just degaussed your compass (BTW, don't degauss unless you are absolutely positively sure you need to).
    • You have taken all the precautions to make sure there are no localized magnetic fields near you.
     
    Kevin Barber likes this.
  4. PhantomPhreak

    Joined:
    Apr 8, 2014
    Messages:
    312
    Likes Received:
    20
    Location:
    The OC in CA
    Can you elaborate regarding calibration on a boat? And the beach? I plan on filming from both. By the way I went to a new location yesterday, twice the compass calibration failed. Worked on the third try but had TBE in hover, but still flew straight. When I went to leave I noticed a transformer humming from a baseball field light pole about 30 ft from where I calibrated. I suspect that was my problem.
     
  5. tferrari

    Joined:
    Aug 4, 2014
    Messages:
    145
    Likes Received:
    1
    I supposed the thread title is misleading, but my post was really more of a reminder to calibrate the compass after advanced IMU calibration/degaussing. Calibrating your compass too often (implying an increased likelihood of the Phantom accidentally accepting a bogus calibration in an area with high magnetic interference) is a likely cause of some of the crashes that users experience.

    Why don't I see "After advanced IMU calibration" on your list of some of the most important times to field calibrate your compass Ian? Am I missing something?
     
  6. ianwood

    ianwood Taco Wrangler
    Staff Member

    Joined:
    Jan 7, 2014
    Messages:
    4,910
    Likes Received:
    1,789
    Location:
    Lost Angeles
    You shouldn't need to recalibrate the compass after an IMU calibration. They're independent from each other. However, often you do both after installing new firmware.

    As for boats and beaches, it depends. A boat typically has lots of things that can make a compass go wonky. Metal decks, masts, motors, etc. all not good for a good compass calibration. A beach depending on it's make up can have iron or other metals in its composition.

    And if you're compass calibration ever fails, you should check carefully as to why. Move to a different spot. Empty your pockets. Take your belt off. Check the mod value. All that kind of stuff. You should figure out why it failed. And you should be even more concerned about when it doesn't fail but the calibration was less than good.
     
  7. WPSPETE

    Joined:
    Jun 12, 2014
    Messages:
    202
    Likes Received:
    2
    Location:
    Vernon BC Canada

    I figured that one out. I did a proper IMU and it flys great.
     
  8. PhantomPhreak

    Joined:
    Apr 8, 2014
    Messages:
    312
    Likes Received:
    20
    Location:
    The OC in CA
    Thanks for the info, appreciate it. I am going to the same spot today and will test it out. Hopefully the lights will be off. If not I will hike farther away.
     
  9. Haze

    Joined:
    May 17, 2014
    Messages:
    150
    Likes Received:
    2
    you dont need to recalibrate that often. I have 1 Phantom 2 that we have NEVER EVER EVER calibrated from factory and never ever ever will untill we notice a problem. I have 2 others that we calibrate every once and a while but not really that often and i travel over 1000 miles to different filming locations and never needed to and never had any issues. The more often you do it the more often you will **** it up. if u notice an issue then do it and leave it alone if it works. thats my 2 sense about the calibration, I have seen idiots online doing it in their house next to their computer and WIFI and then post about problems lol Kids lol
     
  10. tferrari

    Joined:
    Aug 4, 2014
    Messages:
    145
    Likes Received:
    1
    Thanks for clarifying that - much appreciated.
     
  11. evonbart2

    Joined:
    Jun 20, 2014
    Messages:
    43
    Likes Received:
    1

    I can say that in my experience with 5 Phantom 2's.. P2V, P2 and P2V+ that I hadn't done cals at all and had no issues. I did have TBE with one P2, but that has been resolved. I started doing compass cal more frequently because of all the chatter about doing them in every new location and I'll tell you every time I read another forum post - its a completely different story and I wish it would just get straight. Then everyone could follow the same rule.

    The bad thing about what you all are saying is you don't do the cal UNLESS something goes wrong or you notice it acting strangely. Well if my Phantom just turned into a submarine... you're kinda SOL at that point.
     
  12. ianwood

    ianwood Taco Wrangler
    Staff Member

    Joined:
    Jan 7, 2014
    Messages:
    4,910
    Likes Received:
    1,789
    Location:
    Lost Angeles
    There's a LOT of misinformation out there. Never calibrating your compass is bad idea. So is calibrating it every time. You need to know when and where it should be done and when and where it shouldn't. The criteria is pretty simple once you understand what the compass calibration actually does.
     
  13. Haze

    Joined:
    May 17, 2014
    Messages:
    150
    Likes Received:
    2
    thats basically what i said, dont do it if you dont have too and nothings wrong.
     
  14. tferrari

    Joined:
    Aug 4, 2014
    Messages:
    145
    Likes Received:
    1
    No one has said that you should only calibrate if something goes wrong or if it is acting strangely. Certainly if your unit is having presumed compass-related symptoms, you would want to calibrate it -- but this is not the only time you should be calibrating.

    Ianwood has posted in this thread a list of circumstances where you should and should not calibrate. This is probably a pretty good guide for day-to-day flying. And like he said, knowing when to calibrate is pretty simple if you understand what the calibration actually does.
     
  15. Zinnware

    Joined:
    Mar 30, 2014
    Messages:
    174
    Likes Received:
    8