Monk32
lvl.4
Flight distance : 50915 ft
Greece
Offline
|
Someone looking in forum may ask "why so many complanings about lost drones?"
The answer is located in the technical behavior of the pilots and their choosen flight area.
I think many people don't know what they are doing and many times ignoring the statement "compass calibration needed" or "strong magnetic interference".
Lets get explain..
The drone is using GPS - IMU - Barometer and Compass sensors to identify its position, heading and state of flight.
Then desides which mode to use in flight.
There are 3 modes as all knows. GPS - OPTI - ATTI
In GPS mode, all sensors are working to get knowledge and accieving correction and in combination with the barometer mainaining altitude, heading and get exact position state.
In Opti mode (flying under 8 meters of hight) the drone goes when the GPS is unavailable (inside covered places - Under high buildings or other constructions hidding satelites), and it is rellying in barometer - compass and in bottom optical sensors.
In Atti mode (above 8 meters of hight) the drone is practicaly a non sensored device, not knows where to fly and only barometer helps keeping its altitude.
In this cituation any wind drifts away the drone, and if we don't have optical connection with the drone, it is almost impossible to bring it back. The RTH does not working cause the system does not knows where it is and where the home point locating, and this is the reason of losted drones.
How is working really?
The drone needs lots of satelites and a calibrated compass to work flowesly.
But...
When we first activating the drone we are calibrating the compass. Remaining in the same place the recalibration of the compass is not nessecary. But many times the go4 asking to do it. Why we don't ask ourselves why?!!!
Because something is creating magnetic interference making our compass to get crazy. So doing a calibration in the place we've been asked for, in reality we inform the compass the wrong way. As the magnetic interference is there, the calibration makes a wronlgy informed system which when goes up high flying, been now at a magnetic clean environment, the compass and IMU are not in the same state causing the drone behavior to get confused. That's why many guys complaining about their drone strange behavior.
This cituation is called TBA (Toilet Bowl Affect) and it is common among strong magnetic fields. You must have in mind that smart devices, smart watches, Mettal surfaces, Mettalic constructions, fences, Electric Wires, Power lines, hidden mettalic grids and underground wires or mettalic tubes, are making strong magnetic interference which is fooling drone's magnetic compass.
So beware of them and always check out the place you are going to fly.
The GPS signal is not always as correct as we may think of.
No matter how many satelites are located in the sky, the real matter is how separate are according our position.
When many satelites are very close to each other in the sky, lets say 8 of them in an vertical azimouth and only 2 of them lower in horizon, the drone GPS module gets a confused signal, because there is no clear separation between them and the system does not making an accurate trigonometry positioning count.(see the picture with the lines represending the signal from neighboring satelites RED lines ----- are not in clear state - WHITE lines ----- are ok)
That is why some times even if there are enough satelites the drone turns in to ATTI mode.
In this case if the drone is out of our line of sight we got to be lucky to get it back.
This cituation is known as HDOP (Horizontal Degrees Of Position) and is something to get really seriusly.
So ...
DO NOT :
-Let a need for compass calibration pass without serius thinking of which reason causing it
-Ensist to fly in a place with strong magnetic interference like streets with covered wiring lines, near power lines, near mettal condtructions ect or fly between high buildings that blocking sats
-fly without been warned out in case of sudden OPTI or ATTI mode activation
-Rely only on a big number of satelites
DO
-use of some great apps like UAV Foscast (https://play.google.com/store/ap ... avforecast&hl=en_US) which tells you the satelite cituation among other info
-check the area you are going to fly
-avoid flying among high buildings or under satelite blocking places
-avoid flying near mettalic constructions, power lines, and other magnetic field suspect places
Take seriusly the sensor state of your drone and you are going to enjoy your beloved drone for a long long time...
|
|