P4 mind of its own

#1

Hi all
My p4 starts up ok runs ok but recently when it goes up and reaches chosen altitude it drop back down 5 or 6 meters by it’s self .it dosent matter how high I send whether it’s 40 m or 100 m it still drops by itself.
Any ideas ?

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#2

Have you calibrated the compass and drone lately?

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#3

When you say drops, does it fall quickly or slowly,?

Can you visually see the aircraft dropping?

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#4

Yes done imu and compass calibration

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#5

Yes you can visually see it and here it

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#6

Drops quickly

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#7

Have you looked at your flight logs? Anything strange?

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#8

Nothing unusual
Excect small crack has appeared where leg joins main body. Not crashed it only taken off and landed on grass

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#9

Is it while flying forward?

Are you on a recent firmware?

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#10

Have you calibrated the VPS (Vision Positioning System) via the PC?.

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#11

No just straight up not done a firmware update

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#12

VPS effectively is the thing that holds the drone in it’s position, in relativity to the ground.

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#13

Not when it’s 40m/100m up, though.
GPS and inertia sensors only at that height.

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#14

True, faulty barometer?

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#15

That was an initial thought. One with lag.
But at that height (100m) I’m guessing the drop is being indicated by the height displayed in the app, too (since it would be difficult to see)… which comes from the barometric sensor. So that argues that it’s not the barometric sensor.

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#16

I’m just theorising here but usually the IMU calculates the crafts position as well as sensors.

Like a compass IMU exception is caused by the mag heading not corresponding to IMU calculated heading.

If the barometer was feeding the IMU bad data you’d think it would show an exception or error.

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