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Barometric measurement consistently reading negative ground level
573 4 2017-1-18
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Wind Junkie
Second Officer
Flight distance : 116165 ft
United States
Offline

Hello
I've noticed that when vision system is not reading height from the ground, the height consistently reads negative. My picture below is what I took of my Mavic idling in place on the floor in my house. The reading slowly works its way down to negative 2 - negative 4 feet without moving, just idling in place. If I'm outside and I go fly around, when I return to eye level height, the distance reading is again usually negative. Sometimes reading negative 20 feet. I always do a compass calibration before the flight, though I don't think that should matter in this instance. Any ideas why I am constantly reading a negative height? Anything I can do to fix this? It seems specific to the barometric reading since DVS usually is able to properly identify the height.



Thanks
IMG_7352 (1).JPG
2017-1-18
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DJI Mindy
Administrator
Flight distance : 7 ft
Offline

Hello Wind Junkie, please try to do the IMU calibration on a complete flat surface.
Let me know if this helps.
2017-1-18
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Wind Junkie
Second Officer
Flight distance : 116165 ft
United States
Offline

Hey Mindy I'll try and update once I re calibrate. Thank you
2017-1-19
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Griffith
First Officer
Flight distance : 98537 ft
United States
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When you activate the props, do you leave  the Mavik on the ground (floor) for a while,  or ascend a few feet?  

I don't have any knowledge of the barometric sensor location or when, in the initiation process, the reference pressure is taken - immediately upon power-on, immediately upon prop activation, or a few seconds later.  However, I can conceive of a situation where the drone, on a flat surface with props whirling, could create a higher pressure zone around the lower body of the drone during the baseline pressure reference measurement, thus leading to a negative (relative) pressure reading while hovering.

Just thinking out loud :-)  Maybe the DJI software folks could shed some light on the initiation process.

Try ascending a few feet immediately upon prop activation.



2017-1-19
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fans8296c24f
lvl.1

United States
Offline

Griffith Posted at 2017-1-19 08:14
When you activate the props, do you leave  the Mavik on the ground (floor) for a while,  or ascend a few feet?  

I don't have any knowledge of the barometric sensor location or when, in the initiation process, the reference pressure is taken - immediately upon power-on, immediately upon prop activation, or a few seconds later.  However, I can conceive of a situation where the drone, on a flat surface with props whirling, could create a higher pressure zone around the lower body of the drone during the baseline pressure reference measurement, thus leading to a negative (relative) pressure reading while hovering.

Good post even though I have not experienced this, I would love to know what the resolution is for this problem.
2017-1-19
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