Hi,
Specs :
Cube Orange ADSB
Antigravity MN5006
Tmotor NS18*6 Propeller
APD F40 ESC
Herelink
Here3 GPS
Tattu 14Ah 6s Battery
There are very noticeable oscillations in the quad when descending in Loiter and Althold Mode(attached log below)
I suspects Z vibrations are the reason
My props passby the motor mount very closely. See image below
Could this be the reason for my Z vibrations?
Also please comment on my tune. I haven’t tweaked with Loiter params yet
Log :GDrive File
It could be a good idea to space those motors up so the props have more clearance.
Vibrations are definitely a problem.
You might have to do more though, like check wiring pulled too tight or too loose, the usual…
I cant say that vibrations are the cause of instability during descent, it’s probably more general tuning.
Sometimes this instability could be caused by MOT_THST_EXPO set too high. Yours looks OK how it is now. If there’s still issues after the other work (below) you could lower it to 0.7 or even 0.6 . If you did change it you’d have to do some retuning, so leave that as a last resort.
First upgrade to latest stable firmware (4.3.2) and check these new defaults for Cube Orange
EK3_IMU_MASK,7
EK3_PRIMARY,1
I would set these too
BATT_ARM_VOLT,22.10
FENCE_ENABLE,1 ← and check the other Fence params
INS_ACCEL_FILTER,10 ← will be the new default eventually, very safe to use this
INS_GYRO_FILTER,26
LOG_BITMASK,180222 ← reduce the logging a bit unless you really need fast attitude
And these, yours were close and these wont make much difference, but might as well
PSC_ACCZ_I,0.6
PSC_ACCZ_P,0.3
EDIT:
You can also try raising the accel values and see how that affects the stability
ATC_ACCEL_P_MAX,60300
ATC_ACCEL_R_MAX,60300
ATC_ACCEL_Y_MAX,19800
The FFT has picked up on a harmonic, 112Hz, instead of the base frequency probably around 50Hz.
I would say disable the FFT, at least for now, and enable the HNOTCH using ESC RPM data.
FFT_ENABLE,0
INS_HNTCH_MODE,3
INS_HNTCH_BW,25
INS_HNTCH_OPTS,0
INS_LOG_BAT_OPT,4 ← gather both pre and post-filter data
Then I would do
After the tuning and descent rate issues are sorted out, if you are going to frequently swap payloads, then I’d look at enabling the FFT again and check why it’s picking up on the wrong hover frequency.
