fans19db8551
Flight distance : 352851 ft
Singapore
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Lamplighter55 Posted at 6-30 02:16
The compass (actually there are 2 in the Mavic) are the most critical sensors for orientation/direction. GPS lock is secondary in importance as its a constant variable throughout a flight as each satellite signal is captured and then handed off. GPS's primary function is to provide position - not orientation.... so if you loose compass accuracy through interference the drone will register where it is in relation to the constellation of satellites but not orientation - which why all navigation systems still use some form of compass to navigate by. Some aircraft also use inertial systems too - much like spacecraft in order to fix orientation in 3d space - (old days with spinning gyroscopes, modern times with laser beam cavities). I think DJI could improve on how to inform via the console, compass errors and actually not allow a manual takeoff as an extra safety measure that could be user selectable much like RTH attitude settings. One thing I'm now always wary of is 'compass gimbal lock' which seems to be dependent on take off orientation relative to magnetic north. (This is where the craft's compass flips 180 degrees internally - DJI firmware has been written to take this into account but it can still cause a wobble or 'jink'/roll in flight. Looking in detail at the flight log, you can kind of see what happened - when you were still on the ground the GPS was seeing up to 11 satellites but as the craft wasn't moving the compass would have stayed in place - as soon as you took off the compass would have started to drift and then a mismatch would have been registered by the drone software and then negated the GPS input (you can see the moment when on the PhantomHelp.com flight log page - when the GPS bars suddenly turn to a single red bar. At that point your drone is in 'fly-away' state and is drifting in the wind/breeze. Within such a tight space you have little opportunity to try and save the flight by raising the craft to be clear of the trees and near-by building. Once in open sky it might have been possible to regain control as long as you have VLS and RC contact, by switching into sport mode and manually flying and landing as soon as you can in a nearby open space.
thanks for the info.
Actually on my screen, the gps never turns 1 bar and red. the flight record also is the same. that's what perplexes me the most is all the hidden warnings in the flight log text that the user cannot see.
I promise you there was no breeze to carry the drone. it wasn't hovering in atti. It decided to bank sideways in an accelerated rate. it traveled approx 30m to the impact area. that was within 3-4 seconds. when i have looked up, it had already hit. it's why you see no input in either joystick as i had no time to react. if it was 60m away, I would have had maybe a few more seconds? And this is assuming it's at the hit speed of 15+km/h. i'm guessing it would accelerated to max P-mode speed which i think is 30+km/h. So maybe an extra 2 seconds if I was at 60m? If it had cleared the roof, it would have been a rogue projectile flying across the city. Now, I could have possibly raised it to 300m altitude to clear all max city structures but then i'm in violation of the drone rules. It hit the building and it hit nobody when it fell from the air. So maybe it was the best case scenario for the malfunction. |
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