Flying in Auto mode my plane made nearly crashed in the ground making a right turn and decent.

After waypoint 4 a right turn and decent  from 20m to 5 m was requested, however the plane fall to 40cm (above ground), then plane corrected to the requested 5m. After this it made a perfect safe (auto) landing, as programmed.

Before this flight I did an Autotune flight (tuning roll and pitch). (unfortunate no log)

Something is completey wrong, but I have no clou what ??

See the attached, parameter_file, data_flash_log and telemetry_log, the actual take off is at ~70%, the nearly crash at 85%.

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Today I did some more experiments; I changed the PTCH2SERV_D from 0.06 --> 0.02. Unfortunate I could not do the same flight, but I tried to setup a simulair. Perhaps it helped a little, not sure.

What I notice is that going from one waypoint to another with lower altitude,  the NTUN reports the full altitude change as altitude _error, this drives the pitch and TECS. This is a kind of stepfunction, which in a poorly tuned system can results in overshoots. But I'm totally not sure which parameter to tune.

I understand that it is up for discussion, but going from one to another waypoint with different altitudes could also be a ramp function instead of a stepfunction.

Pleas help me in tuning this platform.


The basical problem is an 40% overshoot at a decents, such as decent from 10m to 5m, in between the altitude goes as low as 3m.

Yesterday I tried changing the PTCH2SERV_D from 0.06 --> 0.02 --> 0.01, this had no noticable influence.

Today I tried changing parameters:
Increased TECS_SPDWEIGHT from 1.0 to 1.5
Increased TECS_TIME_CONST from 5 to 7
The result in overshoot is more worse and a kind of oscillating altitude.

I'm really out of idea's how to resolve this, Is the really nobody out there who has a clou ???

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