Hi,

a few days ago i started experimenting with the takeoff-waypoint.

first flight was ok, but since then i have a good chance that the value for altitude is corrupted before takeoff (although i have 7,8,9 satellites)

this might be coincidence and have nothing to do with the auto-takeoff...

i added the log and a screenshot for clarity.

i went through some logs and didnt find anything unusual.

more of these logs are available, on one of them 1500m are "lost" within 1 or 2 seconds, so a mission that was supposed to take place at 150m would have taken place at 1650m (i aborted before i lost sight of my plane)

anyone seen this before ?

what could it be?

regards,

wolfgang

2013-05-27 11-52 2- altitude jumping.log

20130527-jumping altitude pic1.jpg

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Replies

  • Hi,

    I did not study your log so this answer is only relevant for your if you see a large altitude variation shortly after powerup, which then becomes more stable but still wrong by a constant amount -

    The APM uses its "home" altitude through the flight for several things. One of them is to offset the barometer altitude.

    APM is too early in accepting a home position - it often happens (for me) when GPS altitude is still 100s of meters off.

    Therefore, always check alt. via telemetry and re-set home alt. via MP of it is off. Or, press the reset button on APM to captue a new and more accurate home pos from GPS (which is not reset).

    I hope this can somehow be improved soon. Trying myself to come up with a good solution.

    Regards

    Soren

  • Developer

    I'm not a plane expert (more on the copter side) but the gps altitude is notoriously inaccurate especially if you're using a mediatek.  Baro altitude is very susceptible to wind blowing across the baro so if you're apm is out of a case and/or doesn't have a spong over it that could be the cause.

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