HedgeTrimmer
Captain
United States
Offline
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Aardvark Posted at 2018-5-11 16:29
"A warning is not a specificication that Pilots can consider and watch for before hand. "
So do you suggest pilots ignore system warnings ?
"A warning is not a specificication that Pilots can consider and watch for before hand. "
So do you suggest pilots ignore system warnings ?
Did I say that? No.
Warning means something is about to go wrong or already has. Unless you have precognitive abilities you can not take into consideration a warning that has yet to occur.
Where as a specification that should be or must be met can be taken into consideration before hand. Granted DJI would have to provide the how to.
"Compass is not need to maintain XYZ position (as in Latitude, Longitude, or Altitude). Compass is only needed to determine which direction nose of drone is pointing. Inertial motion sensors should be able to tell drone whether it is rotating around compass axis (Z or Yaw). Drone may end up pointing South instead of West, but should not keep drone from hovering."
In theory I would agree with that, but as soon as there is any horizontal, movement (even caused by wind) then any directional, data calculated from change in GPS co-ordinates would conflict with compass data (if incorrect). Ultimately causing the toilet bowl effect as the aircraft automatically tries to correct itself. Any major compass errors in the P4 for example, generate a system message to switch to ATTI mode to preserve the aircraft. In the Mavic Pro the switch to ATTI would be automatic, as I've not seen it yet I've no idea how quickly this would happen.
Movement around XYZ axis (roll, pitch, yaw) should be detected, along with any acceleration changes along XYZ axis (surge, sway, heave) by IMU. All of which should be taken into consideration when there is a Compass Error. Horizontal movement due to say wind should not result in toilet bowl effect. Let alone rapid acceleration.
Anyway, from reading about DJI's system, a Compass Error results in GPS and IMU data being ignored. Which pretty much dooms a drone when pilot is not made aware. Even worse when drone itself seems to not be aware of what mode it is flying in.
"What is needed is for DJI to provide a firm minimum distance recomendation based on actual testing. Along with how pilots can know in advance, not after the fact logs and crashes."
The manual already suggests flying in open areas and avoiding metallic structures, and areas where there might be electromagnetic interference.
A mixing of terms and warnings.
Eletromagnetic interfernce is alluding to interference caused by radio transmissions sources such as Cell towers, high voltage lines, Ham radios, etc.
As for open areas, there in lies a hidden issue. You can be standing in open area, and still have Magnetic Interference - at least according to various statements about Rebar in cement pavement, metal pipes, man-hole covers (I believe that was mine when someone was asking about possible causes), etc. Would be interesting to take a poll of what drone pilots here believe an ''Open Area'' is or means.
DJI makes no statement about avoiding things like cars or motorcycles or how far away (feet or meters) those objects should be prior to takeoff.
On matter of unknown / hidden Magentic Inteference. Unless I already knew there was 5-tons of steel parked in open area, and was specifically looking for Magnetic Interference, I would never have known it based on tests I did. The compass deviations were so subtle that you would write those deviations off as inconsquential. Or a matter of how you held Smartdevice with electronic compass, coupled with walking (body movement / no path to follow).
I did not see any warnings from MPP, CS / GO-4 app of magnetic interference during testing. I did see magnetic interference warning when I took MPP and CS inside a large metal building. So I know it wasn't a case of my MPP / CS having a compass warning turned off, during testing.
In practice how many of your flights have suffered from compass errors, whatever the cause ?
For me it's zero.
None for me yet.
Still based on recent Compass Error / Magnetic Infererence topics - I decided some more extreme testing (aka lots of steel) needed to be done. It is a matter that calls for a reality check, and really calls for DJI to weigh in.
There is an additional concern here about droners wrongly getting a bad reputation from Toliet Bowl effect / unknown Magnetic Inteference / No Warnings. Press, public, and politicians would have a field day if a drone doing a Toilet Bowl effect, ever accelerating to near max speed, flew into a person badly injuring them.
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