f3honda4me
lvl.1
United States
Offline
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To add to what labroides has said, regarding compass on the P4P... When the drone first powers up, it determines which direction it is facing using the compass. (a note about that in a minute) Once it has determined this, it then uses gyro and accelerometers to determine direction and movement moreso than the compass. (not that it stops using compass altogether though) It basically uses these values to help it "fly" straight, etc. If you are near some kind of metal, or other kind of interference (power lines etc) when the drone is powered up, it will cause a bad measurement at start. Then when the drone starts flying and gets away from this interference, it will not be able to make sense of the values it is seeing and it will not fly correctly.
The compass calibration is also equally important to not do near interference or metal etc. The compass is not like previous drones, where you had to do a compass calibration any time you flew from a new region or area. The compass determines the magnetic effect of the area it is flying in when it powers on, so even if your compass was calibrated in china and you fly in new york, it won't affect your compass or your flight, assuming you had a good calibration in china. This is why in the above scenario the drone will fly normal if it starts up near interference and then fly erratic once the interference changes or goes away.
The compass calibration is used to fix issues where the calibration itself is thrown off (get a magnet too close to the drone while transporting for example). Usually the craft can detect this and will inform you that one of the compasses is off (P4P has two compasses). But on occasion it might be only off slightly and you'll notice your craft flies slightly sideways when you are trying to go forward, or it might yaw a bit on its own. Here is where a compass cal can help. |
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