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IMU Calibration Tool

Discussion in 'Pro/Adv Discussion' started by dipicorg, Mar 7, 2016.

  1. dipicorg

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  2. Meta4

    Meta4 Moderator
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    Since weight is critical in quadcopters, I don't think DJI would want to permanently weigh down a Phantom with something that might only get used once every six months.
    It's too easy to just make sure the surface you use is level and have no weight penalty.
     
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  3. alokbhargava

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    This small tool may not be accurate. Go for longer level tool at least 8" as P3 sits on a larger area.
     
  4. dipicorg

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    Sorry Guys, You are all wrong...
    1. You all use the Feets to Calibrate (Level) which ist totally wrong. The Motors are the Point to Measure.
    2. the few Grams do not make really a difference.
    3. After Firmwareupgrades: make a new Calibration, not every 6 Month !

    After a Crash or hard Landing, the Bottom of the QC might not be level anymore.

    Think further....
     
  5. With The Birds

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    And what happens if your crash or hard landing put the motors out of whack?

    Maybe you should remove the main board to do the IMU cal.

    I would rather be flying than wasting time with unnecessary tinkering. Granite bench top is perfectly level and close to fridge. All I need and no issues.
     
  6. dipicorg

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    "unnecessary tinkering" ? I prefer to be in a safe Mode than loosing my QC.
    Btw: if You crash Your QC, what do You think was the Reason for that?
    And why do You try to continue flying a damaged QC?

    I wrote this Thread, because of my personal Experience with
    DJI Drones (P2/P2V3/P3P) and IMU/Compass Issues....
     
  7. With The Birds

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    I said nothing about flying a damaged phantom. You claimed the motors must be used as the reference point for level as the "feets" which I will assume you meant landing gear may not be level.

    I don't need a bubble level in my phantom to get a satisfactory IMU cal, I have an acceptably level surface where I consistently get good calibrations.

    You do whatever your comfortable/happy with.
     
  8. Mark The Droner

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    An interesting idea but probably not best. I agree with Meta4. A few grams matter.
     
  9. Meta4

    Meta4 Moderator
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    Frequent IMU calibration may be popular with some but I have two P3s and I have only calibrated the IMU of one and just once (after a crash) with no worries at all despite many firmware upgrades.
    My feeling is that if it was important, DJI would have suggested it ... and they didn't.
     
  10. DPD

    DPD

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    Does anybody have a definitive answer on how many times or how often you should calibrate the IMU?


    Sent from my iPad using PhantomPilots mobile app
     
  11. Mark The Droner

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    I am not sure there is a such thing as a definitive answer on IMU calibration. There are too many variables. I think the old saying "If it ain't broke, don't fix it" applies nicely.
     
  12. N017RW

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    IMU cal is definitely over-prescribed.

    My P2 has been cal-ed 3 times since May 2014.

    P3, 2 times since purchase mid last year.

    Never concerned with precision of level of the surface.
    (Wooden work bench in garage.)
     
  13. alokbhargava

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    I usually recalibrate IMU immediately after FW upgrade. So far I did 4 times.
     
  14. Air Ontario

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    I calibrate when it is requested, after firmware updates and possibly after a crash/or when flight/hover is abby normal.
     
  15. Numone

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    I calibrate it on our flat kitchen floor. Well OK, before anyone asks, its not perfectly flat; it has 2mm drift N2S over 5.5m and 4.5mm over 11.2m E2W...
     
  16. ianwood

    ianwood Taco Wrangler
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    Putting a level on the body for something you do once every few months is pointless.

    Get a known flat piece of material, place it over motors, put a spirit level across that. Adjust until perfectly level in all directions. Calibrate.

    This would be the right number of times to calibrate the IMU.
     
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  17. RoyVa

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    IMU info:

    Many of us have heard about the dreaded fly a ways. One way to help prevent them is through calibrations. A lot of controversy over what causes them. But I can guarantee you one thing a proper IMU calibration will help prevent some of them. What is an IMU you say. Inertial Measurment Unit is the brains of the quad when it comes to a collection of the sensors and is typically comprised of at least a three-axis accelerometer and a 3-axis gyroscope and employes magnetometers (compass), barometers and other sensor to determine the angular position or attitude of the quadcopter. Basically it's location, direction and altitude at any determined time. Remove any one of the sensors information and you can have a fly a way.
    IMU information is data and data can be corrupted. Sensors can be disoriented. How you say, the main way is by rough handling (shipping), hard landings, crashes and changes to the sensors an compass. These quads are shipped all over the world and are roughly handled so new out of the box they need to be re-calibrated and have fresh data at their new home. After being sent out for repairs and shipped back to you the same is needed. DJI even sends you a email telling you to re-calibrate. Calibration is also need after new firmware updates as new data is introduced.
    Calibration of the IMU must be done with the Quadcopter perfectly level from back to back and side to side. Easy way is to put a piece of glass, cutting board or simular flat panel on top of the quad covering the 4 motors spindles and then using a level front to back, side to side, and diagonally. Placing spacers or paper where needed under the legs to get her perfectly level. Then power up the assistant and the quad and fairly quickly do the advanced IMU calibration. This needs to be done before the main controller gets to warm from no airflow or you may get a to warm message. If it pops right up ignore it. But if the quad had be on for more that 5-10 minutes it may be legit and you'll need to shut down and cool her off for half an hour or so. A clean IMU calibration will only take 5-10 minutes at the most. When completed and after going outside do a compass calibration. When these are completed your quad should now have good data. The Roll, Pitch and Yall of the quad,as controlled by the changes in the motor speeds, will have good and proper orentation around the 3-axis as necessary for input from GPS and compass direction to let her know where she is, where she took of from, and how to get back, as long as you acquire the proper number of satellites and get home lock at take off. When you hover you should see a nice stable hovering quad with minimal drift and have good control of your unit. So when in doubt from a crash or hard landing, do your self a favor and re-calibrate. Do it after having shipped your unit or if it has seen rough handling. Reduce the fly a ways! CALIBRATE !!!!
     
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  18. Imabiggles

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    *GASP* that is no where near level enough, you need a laser aligned three inch ceramic plate and make sure the room is exact 73.4F and during a new moon so the gravitational fluxes dont distort the calibration!! I really think folks put too much though into calibration. If it looks level, its good enough. I get the concept of hobby overkill but it aint that critical. The proof is in the flight - if it holds in place with GPS lock good enough, then the calibration is good enough.
     
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  19. Numone

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    Drat....Drat.... and Double Drat..! I knew it wasn't going to be good enough...:( Well, it'll be it ripped-up tomorrow. Bloody useless builder, giving me a wonky floor.. And... I know, I know... Before you ask no.... OK... I didn't use my all-over body earthing onesy either. I could've doomed me aircraft.... ;)