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Compass(Z) axis issues(URGENT)

Discussion in 'Phantom 2 Discussion' started by hughsnews, Jun 3, 2014.

  1. hughsnews

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    Hi All,
    I have an URGENT issue so if there are any guys who are more technologically gifted than me, I'd be keen for your help.
    I am an archaeologist and I am flying over to take photos of a few sites in Greece in A FEW DAYS. I have a custom mount(made out of perspex etc) that I put small canon cameras into as they are more suited to archaeology. Recently, I have had a few crashes, two whilst flying normally and one whilst using a ground station. What I have done is plugged my P2 into comp and used the compass calibration to check the numbers.

    When I have nothing on the P2 I get this for my compass-X: 311, Y:137 ,Z: -420 . Mod:943
    With mount- X: 134, Y:166 ,Z: -422 . Mod:1238.5
    With plastic Canon A2200 X: 257, Y:175 ,Z: --450 . Mod: 1137.1
    But this is my issue
    I have a Canon S110 which gives off X: 308, Y:96 ,Z: -550(-600 on another test) . Mod:1325

    Obviously, the numbers jump around- but its the Z being over -500 that I think is causing me issues. Today, I had it in the air and it just started to descend(I managed to catch it mid air :lol: :lol: ). The first accident I had I remember I was climbing vertically and it stopped and descended then spun out slightly. My third time it was hovering and then dropped. It's weird as I flew with this camera on for months when I first got the P2 in January with no issues. This is something that has started occuring since march/april but I haven't flown much.

    I have now pieced together the fact that all three crashes I have had has had this Canon S110 attached. It could have two issues- the first is that the camera has a full metal body where as the other cameras I have tested are plastic bodied(like my A2200). In fact if I turn on the quad and measure its compass stats, it jumps even when the camera is off- showing its not a electrical interference. I also wondered if it may be that it has a wifi chip but it gives big readings when turned off.

    I suppose my question is- do you think it is likely this is the cause of my crashes? The fact that the crashes generally occur going up and down verticalluy(which I imagine is Z), seems to show a common cause. I suppose my other question is- if I calibrate(basic and advanced) it still gives me a very low -50o to -620 number, so I imagine that even with calibration, I will still get errors? Or do you think it may be an issue with Quad in general? I just need to know as if my quad is dead- I need to cancel my work. :-(
    If anyone can help shed some light on this it would be amazing as it means I have 12 hours(from now) to find a new camera to attach that doesn't make it crash!
     
  2. sar104

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    Are you sure that you are not just overloading the P2? What does it weigh with the custom mount and S110?
     
  3. mb_guy

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    You would have to wonder about the large metal mass close to the compass as being the issue. Strange things happen, for example I sat mine on top of a closed netbook (off and not charging) when attaching to the naza software and received IMU error 25, recalibrate. Turned it off moved it off the netbook, reconnected to the naza and all was fine.
     
  4. sar104

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    That too, but the random descents sound like an overweight issue.
     
  5. hughsnews

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    Hi All,
    Ok so a few more stats and info.
    Yes I am pushing the quad to its max weight, but it does squeek under the limit suggested by dji.
    I just tested something. So I took apart my mount and swapped around some bits, so that now the camera, although roughly in the same area, is now the other way around. BANG instant change-
    It went to
    X: 364, Y:175 ,Z: -278 . Mod: 849.8

    Now I am curious why this happened- then I realised, the original way I set it up had the battery and based on the camera, I imagine the vast bulk of the electronics on the side close to the Compass. By just turning the camera around, the battery, wifi chip(which isn't connected) etc went to the other side of the quad and a small sliver of the camera next to the lense is now next to the compass.
    So my guess is either the electronics or the battery was causing the Zaxis to go nuts.
    I suppose my original question still remains- IF that Z axis is below -500(and in my case was around -600), would that cause the quad to behave erractically and perhaps try to lower itself down- thus my crashes?!?!?!
     
  6. sar104

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    It may be interfering as you suspect, but you may be misunderstanding the relevance of the Z-axis compass reading. The P2 does not use the Z-axis component of the magnetic field to determine its vertical position or its vertical motion - those are determined by a combination of the barometric sensor and the GPS unit. It uses the horizontal component of the magnetic field to determine orientation in that plane.
     
  7. hughsnews

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    Just to confirm what is the max payload for a phantom 2?
     
  8. ianwood

    ianwood Taco Wrangler
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    Z axis is used for tilt compensation of the compass heading.

    OP, are you recalibrating the compass every time you change the equipment e.g the camera? Also, your compass readings will have a lot to do with the environment you're in when you check it. Finally, you shouldn't have a metal body camera in close proximity to the compass. It will compromise the capability of the sensor.
     
  9. sar104

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    Completely agree, but it's not used to determine vertical position, so while offsets might lead to course errors I would not expect them to cause uncommanded vertical motion.
     
  10. hughsnews

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    Ok so I'm thinking weight may be the issue. Just weighed my bird and it was 1480 grams loaded. Realised since I started flying it I've added prop protectors and fpv which has added another 150gms with my custom mount. I stupidly forgot to weigh. I'm sure the compass readings above may have shown a separate issue that also needs to be dealt with. Could being massive overweight caused a surge ehich caused the drop? Or a relatively quick auto landing?


    Sent from my iPhone using Tapatalk
     
  11. hughsnews

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    I feel like a real idiot now! Gosh. Thanks for all your responses though guys. I'm really appreciative


    Sent from my iPhone using Tapatalk
     
  12. sar104

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    1480 g is heavy, but not unflyable. If the descents are late in the flight it may just be running out of power to maintain lift. If it's earlier then it starts to sound like a number of other reports of sudden descent / autoland. Those seem to be an open issue, but it would still be unrelated to the compass.
     
  13. vaxa

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    Hi,

    I was searching for this problem.

    I have two identical setups. One phantom 2 with with futaba 14 sg and canon s110 (binded to phantom 2 and extra receiver orange on camerargimbal). And one phantom 2 but with s100. Same setup but the camera. I use two different futaba 14sg.

    My setup with s110 has exactly same problem. It has happend 3 times decent. No failsafe yellow flash. The problem started after about 30 flights. No firmware updated before it happend. Also got one crash from same machine when hovering just 2 meters up. Then I bought new phantom to see what happend. Other weird thing happend. Once I lost signal from 20 meter. Once sudden yaw 180 degrees back and fourth. I start to think there was something wrong with one of my futaba 14sg. Then I saw this thread.

    Perhaps wifi can be the problem on s110? Perhaps wifi is always enabled? s100 does not have wifi and so far I had no problem at all.

    500 flights with s100. No problem at all.
    50-60 flights with s110 with two different phantom 2. Problem on both phantoms

    My weight is close to 1500g, but see no problem with that. same weight on both setup

    I will have a new s100 to try.

    Last thing to change transmitter...

    /HÃ¥kan
     
  14. RobertMfromLI

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    People have flown heavier... is the compass still in the original position on the factory leg? If the compass mounting is off a little, the Phantom will fly a little off. If it's off a little more than a little, it will toilet bowl or do other weird aerial maneuvers that make it near impossible to control. I crashed mine that way by just having the compass mounted a few degrees off.