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DJI S800 Zenmuse & wookongM experience + Power Problems?

Discussion in 'DJI Discussion' started by q8khajah, Feb 13, 2013.

  1. q8khajah

    q8khajah Member

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    Posted by q8khajah, Feb 13, 2013 #1
    Hello all,

    So I've received S800 + Retractable landing gear + Zenmuse Z15 + WookongM Rig.

    Worked day and night on assembling and setting up the rig, on Bench got everything right just how I did with my Trex800 ACEONE rig.

    Took the rig on test flight but without the zenmuse. Everything is fine and as expected.


    However, when mounting the zenmuse and making a complete rig including the video transmitter we were up for a nasty surprise.

    when switching on the GPS/Atti , the helicopter seems to be holding fine. but when I start to move around and yawing the helicopter acts as if it lost all power and is descending .. my camera man also informs me that he's losing video feed..

    When I switch the helicopter to MANUAL , it flies perfectly. its only when I switch on the Autopilot that the copter acts sluggish.

    The autopilot settings are as per the recommended setting in the manual.

    The Batteries are from HobbyKing Tunirgy Nano 25C-50C. (Could be the problem we're testing Voltz 65C today)


    Anyone had similar experience? please your thoughts are appreciated.
     
    Last edited by a moderator: Feb 13, 2013
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  2. Bugilt

    Bugilt Member

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    Posted by Bugilt, Feb 13, 2013 #2
    was the video recording?
     
  3. q8khajah

    q8khajah Member

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    Posted by q8khajah, Feb 13, 2013 #3
    well yea, we hit the record button and up we went. But that's kinda irrelevant to our problem I think.
     
  4. fritz99

    fritz99 Member

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    Posted by fritz99, Feb 13, 2013 #4
    Do you use 6S LIPOS ?

    Fritz
     
  5. q8khajah

    q8khajah Member

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    Posted by q8khajah, Feb 13, 2013 #5
    Yes 2 connected 6S packs

    Sent from my Nexus 4 using Tapatalk 2
     
  6. BorisS

    BorisS Drone Enthusiast

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    Posted by BorisS, Feb 13, 2013 #6
    What kind of videos transmitter are you using ? how much A is it drawing ? How and were did you connect the videos transmitter ?

    Dont worry about the c rating of the lipos. 25c even 10c should be enough for the S800 fully loaded running on 6s.

    There seems to be problems at the moment of a rapid descend of WKM setups when flying actually moving the copter arround, you are not the first i am hearing this from.

    What size are your 6s packs ?



    Boris
     
  7. q8khajah

    q8khajah Member

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    Posted by q8khajah, Feb 13, 2013 #7
    Hey Boris, Thanks for your reply.

    I am using DJI's 5.8Ghz video Tx/Rx set with Clover leaf antena's .. The transmitter has a plug that goes right to the AV out port of Zenmuse's GMU. But to power it I am using a 900mha 3S pack. the Antena is mounted on the landing gear (H-Frame) with a bracket supplied with the Tx/Rx set made specifically to fit the diameter of the rods (the rods that you install zenmuse on / battery tray).

    As for how much amperage being drawn, I have no idea, I don't suppose WKM is keeping a log of those.. and I have no way of measuring unless I install something inline between the battery and board.

    I am using 2 5000mha 6S packs in parallel. using TeamLosi big connectors that can handle heaps of amp.

    The puzzling factor is, when im flying Manual, all seem Well and great. its when I turn on autopilot Atti or GPS/Atti when things go funny.. on GPS as I mentioned the helicopter seems to just suddenly wants to go DOWN! as if it lost all power.


    you mentioned people have been complaining about a similar thing? then the problem is worse than I though :(

    btw, I purchased WKM with the V3 GPS .. supposed to be the latest bug-free one.
     
  8. BorisS

    BorisS Drone Enthusiast

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    Posted by BorisS, Feb 13, 2013 #8
    Forget my approach about the VTX. I wasn't aware that you have a VTX DJI setup. I suspected you having a VTX of a different brand needing arround 1000MW which results in drawage that can be problematic if connected directly to the WKM setup of the GCU video out port of the Zenmuse.

    Bug free yes, but i suspect a problem with the hardware directly pointing at the IMU. In Attitude mode or GPS mode the throttle input is not directly routed to the ESCs but interpret by the WKM on the variables it gets from the IMU. Thus the problem could be with your baro sensor or with you ACCs on the Z axis, etc.

    I wouldnt waste anytime and send an email to you dealer and cc in DJI-support or vica versa. This issue shouldn´t be new to them. If it would be a custom frame one could argument that there are to many vibrations acting upon the IMU, but since it is a complete solution the argumentation doesnt work for me.

    You might still get question were and how you mounted the IMU but if you did everything like in the manual and didnt try any experiments it can only be the IMU !

    Boris
     
  9. BorisS

    BorisS Drone Enthusiast

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    Posted by BorisS, Feb 13, 2013 #9
    Was it windy when you were flying ?

    Boris
     
  10. q8khajah

    q8khajah Member

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    Posted by q8khajah, Feb 13, 2013 #10
    There was wind, but not more than what the rig is supposed to handle ,, ie below 28km/h ,, it felt like 20km/h..

    I am scratching my head really, I did everything by the book . but Boris, why would the WKM work great if I simply just remove the load (ie Zenmuse/retractable landing gear) .. it really did feel like the load was inducing something .. even video feed was disrupted when I Yawed. speaking of yawing, oh boy, when I made a full 360 yaw the helicopter was drifting as if i was pushing full aileron to the right side. it was funny !

    I was hoping to try the 65C packs today (even though u were clear 25C should handle the load) however the wind really picked up and I didn't feel I'd get any useful results.. Planning on this friday. I just want to eliminate the possible causes.

    I did email DJI about this as soon as I posted on this forum too. hope I get some kind of an answer..
     
    Last edited by a moderator: Feb 13, 2013
  11. BorisS

    BorisS Drone Enthusiast

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    Posted by BorisS, Feb 13, 2013 #11
    its is an akward one. But one could also look at it from the other side. If it is a power issue why would it work in manual mode. There is no draw difference or minimal between manual mode and attitude mode were extra power is needed for leveling. If it acts normal in manaul mode logically for me there cant be any mechanical or power issue, it can only be the WKM acting strangely and not giving out the right motors outputs in attitude mode and gps mode !

    by the way what lipo may capacaity are you using ?
     
  12. q8khajah

    q8khajah Member

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    Posted by q8khajah, Feb 13, 2013 #12
    You've got a very good point. Sighs..

    I used 2x5000mah packs.. will be using 2x5100mah for the test tomorrow..

    I've been having scenarios in my head and if I discovered that power isn't the issue, the word Interference comes to mind. but nevertheless I will disassemble the main central board and check all wirings and probably shuffle components around.

    Its probably worth noting though highly unlikely as a cause that I have connected the Zenmuse's CAN-BUS cable to the free port on the GPS's cable. The instructions were clear about installing it on any open port. but , I'm just finding any possible explanation until a formal reply from DJI is received.

    Abit frustrated really :upset:
     
  13. tombrown1

    tombrown1 Member

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    Posted by tombrown1, Feb 16, 2013 #13
    You did the compass calibration properly? Waited for home lock (fast green flashes) and zero red flashes before takeoff? Made sure vtx is far from GPS and not pointed at it? (I put a small carbon fiber plate under my GPS just for this reason). Maybe try the exact same setup but leave the vtx unpowered to see if that is the problem.

    I think a previous poster asked if you were recording so that you could post the video here. It may be beneficial to see.

    Best,

    Tom
     
  14. q8khajah

    q8khajah Member

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    Posted by q8khajah, Feb 18, 2013 #14
    Apologies for not replying earlier, I didn't realize there were posts. Yea I looked over just about every sequential step , recalibrated GPS, all initialization wait times. I've had tougher experience setting up ACE ONE on my Trex800E , so I kinda had an idea to follow the book exactly..

    My recent attempt have someone shed light into whats causing my problem. I have used 65C packs and the result is the same, the helicopter holds fine but when moved around I start to lose altitude.

    But I think the main problem which may be causing all of this is vibration. even on Manual flight mode, I deliberately shot the landing and I noticed the vibs. comparing with videos around youtube of other people's S800 I can say my S800 suffers some extreme vibrations.

    Researching more shows some people attempt to balance the motors by finding points where to stick tape as weight and others install aluminum braces to stiffen the arms.

    In my latest test, all I did was sacrifice the retractable landing gear (about 800g) with the stock on and installed zenmuse. so I reduced weight, the copter performed better but not as good as flying it with no zenmuse. The load seems to amplify the vibration problem and it seems to affect the wookong.

    When I fly at Atti mode (No GPS), I can notice the over-corrections .. reducing gain didn't help. on Normal as I said, vibrations show. looks like i have a long way ahead till I get this rig right.
     
  15. BorisS

    BorisS Drone Enthusiast

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    Posted by BorisS, Feb 18, 2013 #15
    is this comparable to what it happening to your s800 ?

    http://www.youtube.com/watch?v=_SrdU6F3vN0

    you see any white or green flashs on the IMU (edit sorry LED i mean )
     
  16. q8khajah

    q8khajah Member

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    Posted by q8khajah, Feb 18, 2013 #16
    wow Boris, this really looks familiar. I can't remember the LEDs as I wasn't watching them was mainly freaking out when the S800 wants to suddenly go down when I move the copter or yaw it around.

    but Yea, very similar experience. I was also wondering if Stress (Load) has anything to do , because this effect is greatly minimized or gone when I fly without the Zenmuse.

    What was the cause of that problem?!
     
  17. BorisS

    BorisS Drone Enthusiast

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    Posted by BorisS, Feb 18, 2013 #17
    cant tell you yet what is going on with the s800 in the video. But its a friend of mine who has these issues since his last three flight now and we cant figure it out. He flew it several times before with the same load etc and now issues. I stronlgy suspect an issue with the IMU. He is wokring on it a soon as he has any further infos i will post it here. But you and him are not the only ones I have heard of this issue two other times on the Rcgroups forum !

    Boris
     
  18. q8khajah

    q8khajah Member

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    Posted by q8khajah, Feb 18, 2013 #18
    Ah, My luck as always :) But it is infact a bit relieving that I'm not the only one.. though DJI hasn't replied me yet and its been several days. Since I am planning on redundancy I may actually pick up a new WookongM , If I do I'd definitely try replacing the components and see if there is any effect.

    But yea Boris, I'd really appreciate any input here, I hope your friend finds out whats the problem for his and mine's sake.
     
  19. Marown

    Marown Member

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    Posted by Marown, Feb 18, 2013 #19
    Hi q8khajah!

    i am a frend of boris. I have the same problem as you can see in the video.
    Im not lucky. at first my s800 fliped and now this ...
    http://www.youtube.com/watch?v=RqhwSX6VXf4

    The only thing i can say i tryed to play with vertical gain and tryed to reduce vibrations with balancing.

    When i fly forward or there is some kinde of wind, the s800 loos violant attitude!!!!
    and after loosing attitude there are 3 White flashes one orange another three white flashes one orange and antother three white flashes and the it is continuing blinking orange ( attitude mode )

    I wrote with terry befor new year in china. He sayed i should damp the IMU with some hard carton. Im not shure...

    Lets see i hope my dealer can help me i will make a 4 houre jurne to him and we try to figure it out what the problem could be!!!

    Thats my Video of this Problem.
    http://www.youtube.com/watch?v=_SrdU6F3vN0

    Oh yes im on 1.34 NOT 1.36 Software

    Tony
     
    Last edited by a moderator: Feb 18, 2013
  20. FerdinandK

    FerdinandK Member

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    Posted by FerdinandK, Feb 18, 2013 #20
    @Marown
    From my point of view this lack of power / the copter is to heavy. I am not saying, that this is your fault, but I assume you are close to 7kg AUW, the outside temperature is close to freezing point, that all together give a lack of power for the copter, as the FC respects your stick input (and flies foreward, and holds attitude). The "altidue hold" seems to have less priority, so it descends. The FC is not able to apply more throttle to the back motors (the special form of the S800 also enhances the problem), so it has to lower throttle on the front motors to keep attitude, so the copter descends. The problem will diminish when temperatures raise in Spring-time, and / or you manage to reduce the weight on the copter, or you could preheat the batteries (and isolate them when mounted on the copter). But the issue/feature is still there, that attitude has higher priority that altitude.

    best regards

    Ferdinand
     
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