Unstable flight in Auto mode - which parameter to tune?

ArduCopter Copter 3.6
1

Dear ArduPilog community,
I have a problem with my mapping-quad (Black Snapper Frame - not symetric but perfectly balanced according to the manual, 15"props, T-Motor AntiGravity 4006, 380kv, Hobbywing X-Rotor 40A ESC, 6S, about 3,8 Kg . I have spend a lot of time with autotune with different settings and wind condition to find a good tune. The quad flies good in stabilize mode and acro (in my opinion). But when in auto-mode I have kind of a not stable/wobbly flight, especially when flying towards the wind direction and on way-point turns.
I have experimented with the Roll/Pitch P/D-value adjustment in flight with no success. Then I have red in some tutorial that the I-Term is important when it comes to smooth flying:
"> gentle, smooth flying for aerial photography requires much lower I-gain than aggressive acrobatic flight"

I have tried to tune a lot but I am still not satisfied. This is also because this copter is used for agricultural missions and the multispectral sensor has no gimbal.

My question is: where should I start, what parameter would be worth tuning or should I go back and do the autotune again, maybe with different settings?

Autotune has been done with AUTOTUNE_AGGR=0,05 to 0,10 (most of the time with 0,05), Roll/Pitch Filters on 10hz (ATC_RAT_RLL_FILT][ATC_RAT_PIT_FILT) - nothing more modified. For each tune I have set all the settings back to standard values.

I have uploaded one logfile and the according video of three flights (one logfile, 3 video files) where I used my best autotune values, then lowered I to 1/3, then raised I to times 1,3). Auto-Mission and wind condition are the same.
Logfile
Video1
Video2
Video3

I could upload more logfiles/videos of different other changed parameters, like loiter pid etc which had in my opinion some effect, this could have also been different wind conditions…

Thank you for any help, it is much appreciated, because I am kind of stuck here with my knowledge of Arducopter…

Lorenz

Here are the used autotune PIDs, the of my autotunes I have also on google drive…:

Date Autotune Session Log File Config Aggr Lipo Filter comment result
23.04.19 5 1 abends Standard Values 0,05 10000 10 no wind on acro a little bit unresponsive but stab ok
INT: ATUN5b yaw very slow
Stab Roll 8,84 Rate Roll Rate Pitch Rate Yaw ATC_ACCEL_R_MAX 55067
Stab Pitch 9,282 P 0,117 P 0,16 P 1,45 ATC_ACCEL_P_MAX 42761
Stab Yaw 3,241 I 0,117 I 0,16 I 0,145 ATC_ACCEL_Y_MAX (mod) 10200
D 0,005 D 0,009 D 0 ATC_RATE_FF_ENAB 1
IMAX 0,5 IMAX 0,5 IMAX 0,5
FILT 10 FILT 10 FILT 1,536

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2

hi @hawaiianer
did you flowed tuning instruction before autotune ?

also check your z vibration there is no clipping but its a little bit high

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with high z vibration you will have position and altitude holding problem

3

Thank you hosein_gh for your reply!
I just discovered those tuning instructions - so I did not follow these. I will try this next week.

About the z vibrations - alt-hold works fine, only in auto-mode the copter will not fly smooth. What can I do to get them lower? Bent motor axis? I did not balance the propeller because they have that 3-hole t-mount system that is difficult to balance with the dubro prop balancer… maybe somebody knows a trick?

4

ok first finish tuning instruction then run autotune
but because of your last modifications i suggest you to reset your parameters to default

a vibration could because of :
-unbalanced propellers
-damaged motor shaft
-using without or not suitable vibration damper
-something transferring vibration from frame to FC

5

thank you for the hints hosein!
I followed the tuning instructions and started from clean standard settings. Only the yaw values that are mentioned in the instructions did not fit my copter - had to increase them a lot to make the copter turn at all.
Anyway, after the autotune and a reduction of the ATC_ANG_PIT_P and ATC_ANG_RLL_P to 50%, she flies pretty well.
I will try to fine-tune the setup according to the tuning instructions and I hope it will make me 100% happy with the tune.

For reference I uploaded one log for an auto-mission with the associated video:
Log
Video

In case somebody else has a similar setup for autotune I created a second thread here: willfollowsoon…