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S900/A2 tipping over at take off from boat...

Discussion in 'DJI A2 & WKM flight control systems' started by BogotaMatt, Sep 7, 2015.

  1. BogotaMatt

    BogotaMatt Big Kahuna @ AirLulo

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    Posted by BogotaMatt, Sep 7, 2015 #1
    Looking for some advice here. I'm currently on a wonderful schooner, and we need to make aerial shots of it. However, upon arming the motors, there's a evident excess of power to the rear engines. Copter is as usual, nothing special, and does that in all modes. I'm thinking that the boat movement is confusing the A2, and upon giving it the beans to take off same thing happened again, rear motors spool much harder causing it to tip. Nothing broken, just confused. Any idea ?​
     
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  2. cootertwo

    cootertwo Member

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    Posted by cootertwo, Sep 8, 2015 #2
    Just a guess, but most flight controllers require a stable, non-moving platform to initialize properly.
     
  3. Motopreserve

    Motopreserve Drone Enthusiast

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    Posted by Motopreserve, Sep 8, 2015 #3
    I think @cootertwo@cootertwo is right. Any time I've read about boat launches, the calibration/startup was done on the dock before heading out.
     
  4. Pumpkinguy

    Pumpkinguy Member

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    Posted by Pumpkinguy, Sep 8, 2015 #4
    This is a prime example of when to take off in atti. gps home point could change by 30' from when you arm the motors to when you actually take off. The craft wants to immediately fly to the home point = tip over.
     
  5. dazzab

    dazzab Member

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    Posted by dazzab, Sep 8, 2015 #5
    Boat launches are tricky for the reasons mentioned above. The movement during initialisation can really upset the flight controller. Interestingly enough in the Pixhawk/Arducopter world they are even working on a specific 'boat mode' to work around these issues.
     
  6. Carapau

    Carapau Tek care, lambs ont road, MRF Moderator

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    Posted by Carapau, Sep 8, 2015 #6
    The A2 will indicate via the LED if there is an issue with the IMU calibration on start up. I have, as have many others, successfully launched from boats many times. Admittedly the swell was only slight so in a heavier see you may have issues. As for the A2 trying to fly immediately to the home point, this is not the case. Again I have powered up the aircraft numerous times in one spot, physically moved it to another (eg on a moving boat) and it has taken off perfectly. This is just a myth and the cause of such tip overs or movements on take off is caused by something else entirely. Check your system thoroughly on ground first and then ensure that the boat is not emitting strong RF from things such as radar and its own radio systems. Check that it is not causing magnetic problems due to its structure. If need be try taking off from the boat whilst it is in dock.
     
  7. Pumpkinguy

    Pumpkinguy Member

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    Posted by Pumpkinguy, Sep 8, 2015 #7
    I didn't mean to post misleading info. I was told by a few people about her trying to move to home point immediately after takeoff. I just believed ot to be true. I blamed it for a tip over I had. Lol
     
  8. BogotaMatt

    BogotaMatt Big Kahuna @ AirLulo

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    Posted by BogotaMatt, Sep 8, 2015 #8
    That was definitely the movement of the boat. We were on a schooner in a formed sea, we changed plans and took off from the beach. Problem solved, shot in. A technique we later tried is to hold the copter still off the deck while powering on. I got a stable arm and liftoff.
     
  9. stevemaller

    stevemaller Heavy Lifter

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    Posted by stevemaller, Sep 9, 2015 #9
    The ALTA and MōVI both have "motion booting" to deal with this. They just use the last good value for gyro calibration.

    This doesn't address the issue of the GPS home position, but that's going to be a problem that can only be solved with something on the LZ. Best solution would be a mobile app that constantly uploads the latest "home" position, but in the case of a true failsafe/RTH scenario, presumably communication would be lost from the ground, and your bird would be wet in no time. :(

    I guess you could also have some kind of LZ beacon that the flight controller could seek out, but I am not aware of anything in the civil realm that has anything like that. I'm sure the military guys have figured that one out.
     
  10. BogotaMatt

    BogotaMatt Big Kahuna @ AirLulo

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    Posted by BogotaMatt, Sep 9, 2015 #10
    That's a great asset. We tricked the A2 into thinking that it was stable powering the bird holding it in up the air. And yes, any failure and that's a wet bird.
     
  11. fltundra

    fltundra Member

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    Posted by fltundra, Sep 9, 2015 #11
    The cell phone in your pocket.:) I'm sure they have something in the works. Say switch between follow me mode to return to current pos.
     

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