PosHold not working properly

I have used Position Hold before but for whatever reason now it seems to work at higher altitude but not at lower altitude.

It seems that the Desired Altitude is stable at higher altitude in my case (35-40 meters). When I try to enable PosHold at around 15-20 meters, the Desired altitude drifts downwards even if the throttle stick is neutral. I have tried with a laser altimeter to maybe increase the altitude accuracy but with no luck. Look on the graph. The blue line shows stick position, the red one is desired altitude and the green one baro altitude.

3691314014?profile=original

Here is my log file

2016-08-18%2015-23-28.bin

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Replies

  • Rene,

    Try maybe bumping up the throttle accel, throttle rate, and altitude hold PIDs. Start by knocking up the P values by about 5%-10% and if that has an effect dial it in with the I values. Hope this helps.

    Cheers,

    Will F

  • Hi Craig,

    I tried AltHold only and it behaves like PositionHold. At low altitude, the hex drifts downward exactly like in PosHold. I haven't tried AltHold at higher altitudes (> 20-30 m).

    I did the mid throttle calibration so that the hex hovers at 50% throttle. We can see on the graph that when the throttle is level, the DesiredAltitude goes down which shouldn't happen at all.

    Thanks,

    René 

  • how well does loiter and alt-hold work?

    When you hover in stabalize mode where is your throttle at on your radio? Above 50%, below 50% or right at 50%?

    the logs don't show anything really out of the ordinary. I've never personally used + on a hex (i always use X) but I don't see how that could be an issue here.

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