Slow IMU initialization and Sensor errors?

Discussion in 'General Discussions' started by Syrne, Nov 1, 2016.

  1. Syrne

    Syrne New Member

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    I can't be the only one having these issues, but I did not see it mentioned anywhere.

    After updating the firmware for my Mavic Pro, about 70% of the time I turn it on it sits at "IMU Initialization. Please do not move or turn off aircraft" comes up and sits there for at least 5 minutes.

    And also about 50% of the time I fly, I eventually get a "Front left sensor error" during flight which always scares me into landing the thing. I haven't been able to fly for more than 10 minutes without this error coming up.

    I restart the aircraft and then it seems all is normal again and I get the green "Ready to go" notification. Then, after taking off and flying for about 5-10 minutes, I get the "Front left sensor error" once again while flying far away from any obstacles!

    Is this a firmware issue? Is my craft defective? I have checked all of the sensors and they all seem perfectly fine! Nothing is blocking the lenses of any of the cameras. I have no idea what could be wrong, but I do not feel comfortable being 400 ft in the air and having a big red "SENSOR ERROR" notification on my screen. It really sucks because I can't get consistently good footage if this keeps happening. :(

    Thank you for any help!!

    EDIT: Sorry just realized I posted in general discussion and not the Mavic Pro board. Could a mod please move this or I delete and I will repost there?
     
  2. Hoobashoot

    Hoobashoot Member

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    Calibrate imu in a cooler environment. It should fire up quicker. That was the case with p4
     
  3. Parker

    Parker Active Member

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    I keep seeing this answer everywhere. I am confused... so every time I fly I have to find a cold spot to calibrate the IMU? Or will doing it a few times in a cold environment *fix* it so it does it faster? Mine seems to calibrate almost every time I fly, takes a little while. pretty annoying.
     
  4. kmaluo

    kmaluo Well-Known Member

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    Did you calibrate before the first flight? DJI actuality recommends against it. Anyway, get a good one in a cold environment, then you should be good to go.
     
  5. Hoobashoot

    Hoobashoot Member

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    Calibrate imu in cool flat spot. Calibrate compass in an open field away from anything metal. Only recalibrate compass when it recommends it or you travel a good distance away. Imu should not need recalibration.
     
  6. Raptorman

    Raptorman Well-Known Member

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    There is some debate on the issue of calibration and perhaps the Editor can chime in and set folks straight on the matter. As I understand his recommendation and I'll defer to him if he follows up, but as I recall he does recommend IMU calibration upon receipt because there's no way to know just how roughly the unit was handled in shipping and if it is jarred sufficiently the IMU would need to be calibrated. If you don't know how it was handled then calibration is advised.

    Additionally, as with other DJI drones, you must perform an IMU calibration after any and all firmware updates. I have seen nothing to indicate the Mavic Pro is unique so, once again, if you do a firmware update you must then do an IMU calibration.

    The secret to doing an IMU calibration is: make sure the bird is not warm before performing an IMU calibration so if you have had it powered on to change settings or just to play with it turn it off and leave it off until it's cooled down -- I'd say at least 30 minutes and 60 might be preferred. Also best to do so in a place that is not hot as high ambient temperature will make the drone hotter quicker. Find a flat, level surface that is not likely to have much vibration -- concrete is great for that. Make sure the surface is level because that level is referenced in flight and can effect the camera/horizon tilt. Also, while performing the IMU calibration do not walk around as the vibration from your feet can effect the calibration. Lastly, this is best done indoors so as to prevent wind from inducing any vibration or movement while the IMU is being calibrated.

    The compass calibration, when it's required, should be done outdoors and away from power lines or ferrous metal -- anything that might skew the magnetic field and compromise the compass calibration. The compass is a surprisingly important component and can have a huge effect on flight control so don't mess that up -- bad things can and have happened.


    Brian
     
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  7. Mako79

    Mako79 Well-Known Member

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    +1, a few things to note.
    DJ Turbo/DJ Tahoe ED/etc all said to NOT do the IMU as they done in a 'controlled climatised' room. The problem here is that do they climatise the room for the correct country? I don't think so.
    The reason for the longer IMU warmup is that Mavic is now in a country that is cooler than where it originally got calibrated.
    I do think everyone should do an IMU calibration - why? because the drone could of been miss-handled during delivery and they could of done a firmware update and didn't bother recalibrating.
    And also note, the calibration is now a 5 axis calibration. Belly, side, side, back and bottom. So make sure you do the calibration the moment you turn on your mavic. The quicker you do the calibration, the quicker your warmup times will be.
    And don't put it in the freezer. You will get condensation in the lens.

    IMU:


    As for sensor (it could be the same method as the P4):
     
  8. kmaluo

    kmaluo Well-Known Member

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    But don't you think that the people who design and service the Mavic know better than people who are basing their assumptions on past DJI models? Is this the same IMU chip? Is it integrated the same exact way? Just seems like engineering would know what they're doing, and would account for varying climates and transit stress.

    I haven't calibrated my IMU even after a firmware update. Levels are fantastic and operations have been flawless.
     
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