de/MagnetError








Info

The MikroKopter uses the GPS in cooperation with the compass to automatically maintain the direction of flight when the GPS function is switched on (PositionHold, ComingHome, CareFree).

If the compass is disturbed due to incorrectly routed cables on the copter, incorrect calibration or external influences, the copter can no longer determine the correct (flight) direction (despite GPS). This can lead to deviations from the trajectory / misconduct or "messing around" / circling around the position at PositionHold.
A detected error is then indicated by the error message err22 in the telemetry display.






The "Magnet Error"

Since firmware version V0.86, the magnetic value of the compass sensor has been checked even more precisely and displayed in the event of an error.
If the error occurs, one has to differentiate between:

  1. Error in the calibration
  2. Error before the start
  3. Error in flight




Error in the calibration

In order for the compass to work properly, it must be calibrated correctly !!!
The magnetic field and the inclination are set here.

The critical ranges for the magnetic field are below 80% and above 120%. If this magnetic value falls above or below this range, a malfunction occurs. Therefore, the value should be around 100% after calibration. This is the only way to have a sufficiently large tolerance for the "critical limit".

With the Inclination the earth's magnetic field is also taken into account. The value that should be reached here is shown in brackets in telemetry (for Hamburg/Germany e.g. 68°) . That is why it is important when calibrating that the copter is calibrated / rotated in the north / south direction. Calibrating in a different direction leads to a shift in the value and to incorrect behavior - even if the magnet value is correctly calibrated !!!

(INFO: The Inclination for the flight location can also be checked here: Link)

  • The calibration of the compass AND the control of the values are described here: CalibrateCompass




Error before the start

If there is an error message before the start, iron or magnetic material is probably involved.

/!\ The copter cannot be started !!!

The possible causes can be:

  • Reason:There is iron or magnetic material under the launch site
    Remedy: Start from another place

  • Reason: An attempt is made to start from a ship
    Remedy: If the starting place cannot be changed AND the magnetic problems are demonstrably ONLY at the starting place ~ - (iron / metal under the copter) - ~, the function Kompass_Fehler can be activated (Link). This function SHOULD NOT BE PERMANENTLY ACTIVE !!!!!
    TIPP: If you start from a fluctuating boat, you should also use the Boot mode function (Link).

  • Reason: The copter moved during calibration / activation (throttle up + yaw left)
    Remedy: The copter may not wobble -> recalibrate / activate




Error in flight

The magnetic value must not deviate by more than 20% even in flight (less than 80% / greater than 120%).

INFO: Incorrect inclination is not reported in flight, only the 20% deviation of the magnetic field.

If the error occurs in flight, it can have the following causes:

  • Reason: The copter flies in the immediate vicinity of e.g. Electricity pylons, a construction crane, other large metallic objects
    Remedy: Carefully fly the copter away from the interference field
    INFO: Usually there is no major impairment in flight behavior.
    If the flight behavior is faulty, the GPS MUST be deactivated (PositionHold or ComingHome OFF / CareFree OFF) and the copter must be flown out of the danger zone manually !

  • Reason: Poorly routed power cables in / on the copter: The copter displays the error message (err22) when accelerating or with a heavier copter
    Remedy: Twist the live cables on the copter and re-route if necessary






Detect magnet errors

The values for the magnetic field and inclination can be read in the transmitter telemetry (Jeti and HoTT) or in the KopterTool:

http://gallery3.mikrokopter.de/var/albums/intern/HoTT/Display-Telemetrie-einfach2.jpg?m=1438861939

  • Graupner HoTT

    The magnetic value and the inclination can be viewed via "text telemetry".
    Here you can see how to open "text telemetry": LINK
    To see the values for Magnet / Inclination in the penultimate line, press the "SET" button again.



http://gallery3.mikrokopter.de/var/albums/intern/DC-16_001/JetiBox/JetiBox-MagWert.jpg?m=1585653565

  • Jetibox
    With the Jetibox, the arrow is pressed to the right until the display for Magnet / Inclination appears.







http://gallery3.mikrokopter.de/var/albums/intern/MK-Tool/Display/KopterTool-Virtual-Display-Magnetwert.jpg?m=1585646705

  • MikroKopter-Tool

    You can find the display in the KopterTool under the "NaviCtrl" button. Here then in the virtual display with the red arrow keys right or left until the display appears.






Is shown:

  • the magnet value in% (should be around 100% (+/- ~5%)
  • and the measured inclination in ° + the inclination theoretically present at the calibration site in brackets.


For Info:

  • Before starting, the magnet value should be between 95 and 105 and the deviation of the inclination should be less than 3 °
    (otherwise you have to recalibrate ACC and compass (or there is iron in the ground = search for a new starting place))

  • When hovering, the magnetic value should be between 85 and 115 and the deviation of the inclination should be less than 5 °
    (otherwise magnetic fields of the cables laid in / on the copter interfere => twist or re-lay)

  • If you accelerate hard in flight, the values can run out of range. When hovering again, however, they have to adjust again






Remedy for current errors

If the magnetic fault is due to poorly laid lines, one should:

  • first look at the plus and minus lines from the Lipo and to the BL controllers
  • Lay the outgoing and return lines in parallel on the power lines and do not make loops on individual lines

  • If necessary, twist the wire pairs slightly
  • Increase the distance between the compass sensor and the cables
  • One reason can also be the internal structure of the lipos! Eneither use another Lipo without magnetic fields or, if necessary, increase the distance between Lipo and compass






Videos

In these videos you can see how magnetic fields arise and what effects they have:

# https://www.youtube.com/channel/UCVtNnQy4UZBykpSDjCCmUUw?view_as=subscriber



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