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degauss my compass

Discussion in 'Phantom 2 Vision + Help' started by sdtag, Jun 29, 2015.

  1. sdtag

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    I searched for this and came up empty. It must be in here somewhere but I couldn't find it.

    I use Dashware a lot on my flight videos. I have been noticing lately that my heading or compass data jumps around a lot in my videos.



    It is making me nervous because I think this is the start of a fly away condition. The compass is giving out erratic data. With my Phantom hovering looking in one direction you can see the data flip 360 180 360 180 This can't be good or even ok.

    Do I need to degauss my compass? How exactly do I do that? How strong of a magnet? How far away? What kind of motions? Circular I assume. Or should I just replace it?

    Thanks in advance.
     
  2. sdtag

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    This is what I found so far.

    You need a fairly strong but small magnet and need to move it around in a figure of 8 motion and in three planes, x, y and Z. You can usually do this in about 5-mins from start to finish. Concentrate on 8 shapes and also do underneath the compass if you can. You have to get quite close.
     
  3. Mako79

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    DONT DEGAUS THE COMPASS!!!

    I don't use dash ware so I do not fully understand the heading variable in the app. Is it relative to true north heading or is Heading VS you/smart device/home-take off point? How I interpret this is that the home/take off point is a GPS value with tolerance and is inaccurate to +/- xx ft.. This means the GPS home position constantly moving. What makes it worse it that you are standing TOO close to the phantom, it is calculating the take off point and where the phantom is. If you really want to test, use the RADAR and fly a good 20 metres away and then watch the heading values. Another test would be to get a laptop and go in an open field and check the Compass MOD value. should be 1300-1800 (1500 is nice).
     
  4. sdtag

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    it is relative to true north.
    I think I did have the home point set to dynamic.
    I will try it again a little farther away but I have lots of other videos and flight log data that show the same thing.
    Thanks but I still think it's the compass.
     
  5. sdtag

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    I degaussed the compass
    I leveled the Phantom and reset the BTU and did advanced calibration on the IMU.
    I took it outside and did the compass dance.
    I did a couple of short, nervous, test flights.
    My compass data still jumps around.
    And when I spin fast, sorry, yaw at a high rate, it is perfect. It spins like it is on a pole.
    However, when I try to yaw slow, it makes a 10 foot circle.
    Should I be concerned? Anyone?
    Think I should just replace the compass? I am thinking about it.
    BTW this is a P2V+v3
     
  6. Mako79

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    Go outside with a laptop and a long 2 mt usb cable. Check the compass mod values. Between 1200-1800 is good.
    Ignoring the Dashware, whats the DJI app radar displaying when you fly? does is spin? How many Sats you getting?

    Yawing is to do the with ADv IMU calibration.
    Get a spirit/bubble level and make sure its perfect on ALL AXIS = Left and right, front and back = dead flat and levelled with horizon..
    Keep the phantom off and keep her cold to increase the chance of avoiding the MC temp too warm warning.
    I have the PC and the Phantom assist ready - Plug phantom in and the moment the phantom is on, i calibrate immediately.

    It wouldn't hurt to upgrade to the plastic-anti static V3 compass. They are cheap.
     
  7. yorlik

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    SCARY! I'm with you, I would have to do something, I could not fly with that!

    first thing i would do is watch compass on app and verify it too is doing this. it could be a uf log sdk bad data feed. so is app doing it too?

    if not, then i would report it to app designer to fix.

    if so, i would try degauss with my 500 watt ac solder gun, and if no change, i too would buy a new compass b4 flying again.

    btw, is compass solid sitting on ground b4 motors on? solid on ground motors idling? read smooth while just holding and rotating?
     
  8. sdtag

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    I ordered a compass on Amazon. It was 18 bucks and I signed up for an Amazon credit card and it gave me a 10 dollar discount so my compass was 8 bucks!
    Plus a lifetime of paying 28% interest. haha no I pay my cards off every month.
    I'll replace it and try it all again.
    I think I'll try the refrigerator trick before I do the advanced calibration again.
    Thanks for your input.
     
  9. sdtag

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    I checked some of my videos and data from a couple of months ago. It was fine then. Whatever is causing this is progressively getting worse and worse. That's what made me key onto degaussing the compass. I thought it made sense, it was absorbing magnetism. Either I didn't degauss it correctly or this isn't really my problem.
     
  10. sdtag

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    To be honest with you guys I never really paid any attention to the compass in the app.
    I tried it right now. I am in my office. I left the props off. I powered up the TX, the wifi extender and my tablet. Then the Phantom. I actually got 6 sats inside my office! I started the motors and picked it up and moved it around almost like the compass dance. The compass in the app is perfect. It follows every move. Now I am really confused. I'll load the video and data and see if it followed the app compass or if it still jumps around.
    So far I have using DJI Ultimate Flight because it will log my flight data. I like this app but I guess now I will have try some more to see if they do it also. Maybe it's the app? I don't think so but I will check it out.
     
  11. yorlik

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    might not be equiv you carrying it around, but very interesting it is solid. I will check my logs lately and see if they too show crazy data.... I real flying is rock solid in app then it is pretty indicative of the log data has an issue!

    maybe check your dashware and make sure it is really compass variable you are watching!
     
  12. yorlik

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    just checked my last log from a couple days ago - about 6 minutes flight time.... variable is YAW I believe, and mine is rock solid, slowly changing as I appeared to rotate it. staying steady +/-1 degree while not changing - probably 1 minute at a time steady, then rotate maybe 6 times in the whole flight....... hope you find your dashview has mixed variables and is showing some other column! check your csv file your self and see if YAW column is indeed as steady as your compass in app showed.... hope your dashview just mixed up the YAW variable for something else...
     
  13. sdtag

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    I thought there would be a column for heading or compass but I guess it is yaw.
    Mine is all over the place. 358 to 23. 87 to 110. 173 to 342. 184 to 99. 358 to 23 to 71.
    in 7 adjoining cells it goes like this: 93, 91, 355, 359, 358, 254, 190.
    It has periods where it does appear to be solid, then it starts jumping around again.
    so if my yaw data is jumping around but the compass in the app is correct, what the hell is going on? Now I am really confused.
    I'm looking at the pitch and roll columns now also. They are pretty solid except once in a while they make a big jump also. My roll column was all zero's and one's, the it jumps to 15, then -4. Same for the pitch column. zero's and one's then from -2 to 13 and back to -2. And never at the same time as the other columns.I think I'll go back and start looking at all these csv files and check these columns.
    I'm going to replace the compass anyway since it's on order. I hope it makes a difference but at this point I think it's something else. loose cable connector? I'll find out in a day.
     
  14. yorlik

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    Remember that acceleration from stick movements is VERY fast - easily less than 1 sec, prob less than 1/2 sec when moved from center to extreme end. This means your flight log with standard 2 sec update time WILL show pitch and roll changing from nominal near zero to HUGE number from one frame to the next. If you set update time to .1 sec like I have, you would probably see those pitch/roll changing smoothly... So I would not despair over them. So something appears wrong on your yaw readings for sure, but remember too: I think you are remembering the many videos posted where the compass begins to go crazy just before a crash: yours is NOT doing it like those videos: they all had good compass readings, then it SLOWLY began to show yaw changing then crash - yours is very fast almost random changes, not the slow yaw over 180 degrees, so I don't think it is the same kind of issue.... Obviously let us know if the new compass fixes it!
     
  15. sdtag

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    I have it set to 1 second. I went back to my earliest flights with Ultimate Flight and checked the data and loaded the video and data into dashware. Same thing. This has been doing this since day one, April this year, I never noticed. My yaw column data is all over the place. I put a post to Ken on his google group. Now I'm starting to think it's the ap. I have only used Ultimate flight so far. My fault. I'll try some other apps after I replace the compass. I'll make some flights with ultimate flight and vision pilot and FPV booster. I think these have flight logs.
     
  16. yorlik

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    REMEBER the app just calls SDK data... many of us do not have this anomoly in our SDK log dat via UF... therefore I don't think you can blame the UF app itself for this...
     
  17. sdtag

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    yeah I asked Ken and he answered me pretty quick.
    I asked him if this was hardware or software.
    He said the same thing - hardware.
    I just received my new compass. I'll get in tonight and try it out in the morning.
     
  18. IflyinWY

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    Where the deer and the antelope play
    #18 IflyinWY, Jul 3, 2015
    Last edited: Jul 3, 2015
  19. sdtag

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    wow cool page - nice links
    thanks
     
  20. sdtag

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    I did some flights this morning. It was flying well and it felt good. I did another hover test and generally played through 2 batteries. The compass in the app was perfect. It felt like new again and I just knew I fixed it.
    I had one instance where I launched and went straight up about 40 feet and hovered. All of the LED's turned solid red on all the arms. That is quite a sight. I swallowed my tongue. I still had control and landed immediately and re-booted everything. No message on the app. Everything was fine after that. ???
    Later when I got home and loaded a flight log and video into Dashware, it's still doing it. It's not as bad as it was but it's definitely still flips 180 degrees. Looking at the csv file again it's better than it was but I think the root cause is still there somewhere. Where do I look now? Is this coming from the flight controller? If it is flying perfect and feels good, maybe I shouldn't worry about it? I'm trying not to be overly paranoid but I don't want to see $1200.00 fly off.
    my test:
     
    #20 sdtag, Jul 4, 2015
    Last edited: Jul 4, 2015