4.3.7 - sudden quick pitch/roll during landing after successful autotune (possibly dangerous)

ArduCopter Copter 4.3
1

please see logs:
https://drive.google.com/drive/folders/1rP3nLsUY7yolBrk13ye2zFJd5ub1R7Jw?usp=sharing

Screenshot from 2023-06-07 13-28-40
Screenshot from 2023-06-07 13-28-40852×386 64.5 KB

Screenshot from 2023-06-07 13-30-45
Screenshot from 2023-06-07 13-30-45852×386 37.2 KB

Additional information;
The copter did fly well after autotune.
On every landing (still in autotune, after a successful tune), as approached the ground, it did a sudden attitude change. At least once per landing.

Not reproducible in the test following flight. (stabilize/althold/poshold/loiter) - all behave as expected.
This seems to me like something very off happening only after a autotune.
Please note that the first tune was Yaw, the second Pitch, and both produced this nasty effect.
Rangefinder is present.

(and why are there so many CAN messages spamming the messages?)

2

CAN spaming usualy comes for an old Here3 GPS module.
If you have one, update the firmware of the GPS.

2 Likes
3

Thank you - will do.
Any thoughts on the landing issue?

4

All I can think of it might be an issue with the MOT_THST_EXPO you have set.
I would try something slightly lower, like 0.76 and test with ascents and descents.
You may need to retest and set MOT_SPIN_ARM and MOT_SPIN_MIN.
Hover thrust might need to relearn a bit - then you will have to check these:

INS_HNTCH_REF  // use hover thrust * 0.7
PSC_ACCZ_I  //  hover thrust * 2
PSC_ACCZ_P  //  = hover thrust

Depending on the differences in flight, it might even be worth running Autotune again - especially after these recommendations below based on your existing params, which will get the Harmonic Notch Filter working as it should:

INS_HNTCH_FM_RAT,0.7
INS_HNTCH_REF,0.133
INS_LOG_BAT_OPT,4
PSC_ACCZ_I,0.4
PSC_ACCZ_P,0.2

Also set this boot delay when using CAN devices, it may not be entirely necessary but is recommended and cant hurt
BRD_BOOT_DELAY,3000

It would be good to see a log of flight after all this - or at least after the Autotunes.

1 Like