X8 Setup Motors are oscillating

[Marco]

Hello to everybody,

I have a X8 Frame Setup and since the first flight i have the problem, that the motors are oscillating.
The Octo is able to fly and also the position hold works, not good but i can leave my fingers of the transmitter.
But there is always the "oscillating sound" from the Motors, and the copter flies not well.
Also i can command roll and pitch, but as the copter stops the movement it shakes, sometimes nearly not, sometimes
very heavy...
First i thought PID tuning is the key... but i can´t find a setting...
Right now i think about vibrations.
Do you agree with me, that in the picture below the "imu acc x" is much to high?
Also "imu acc y" shoulb be lower?
And can anyone give me an idea if this vibrations can lead to oscillating Motoroutput??
I also loaded a small log file from a short flight in my garden to dropbox(file was little bit bigger than 5MB)
Can be downloades using this link: https://www.dropbox.com/s/1cb0x8p4mgd3j0p/021-AQL.LOG
I am thankful for any help, idea or experince someone of you had made.
If any further infos are needed, please let me know

many thanks in advance
greets Marco

[Trnquill]

What ESCs are you using? If ESC32, what mode? If closed loop RPM, have you tried tuning the PI values of ESC32?

When swithing from smaller to larger props and slower motors I started experiencing the same behaviour as you described above. Oscillating or "whining" and pulsating sound of the motors and very rapid and low amplitude vibration of the arms. The reason was poorly tuned PI controller in closed loop RPM mode of ESC32. Since my helicopter is new and I haven't had time to tune the PIDs in AQ board I decided to take one step at a time and switched the ESC32s back to normal mode (open loop?). The problem/oscillation was gone immediately.

Maybe after I have my AQ tuned to perfection I will switch back to closed loop RPM mode and tune the PI settings of the ESC32s to get a smooth ride. Since there's no tuning guide for the ESC32 closed loop mode you have to tune it by yourself via trial and error and lucky (or educated) guess.

[epyonxero]

Which firmware version are you using?

[Marco]

oh I missed importand information...
I´m using ESC32 with Firmware: 1.4.5082
ESC´s are running in "open loop" mode since the first flight.
I never tried tuning PI values of ESC or closed loop mode yet.
Next step: I will flash Firmware 2.0 ore are there any objections?

More about the Copter:
- Frame: rosewhite Tamara X8
- FC Firmware: 6.6.1 r165 b1036 HW v.6r2
- Tiger Motor´s MN3508-16 KV700
- Tiger Motor´s Carbon Props 13x4,4
- 4S 10.000mAh LiPo Battery

Regards
Marco

[chschmid]

[axelnied]

[chschmid]

Hi Marco
in the hex x setup I used the mixing here:
I do not say that this is the ultimate solution. It just worked for me on this setup and FW.

PortOrder=3, 10, 9, 8, 1, 2
[Pitch]
Motor1=-80
Motor3=80
Motor8=-80
Motor10=80

[Roll]
Motor1=40
Motor2=80
Motor3=40
Motor8=-40
Motor9=-80
Motor10=-40

You find some background about mixing tables here:



Cheers
CHristof

[Marco]

Hello again,

I have updated all ESC32 to Firmware 2.0.0.6129
Today i was out for a testflight.
Result:
- Motors show still same behavior
- PI default setting needs adjustment, due to Motors wont really start.
4 to 5 attempts are necessary unti all motors are runnig.
- and last but not least after a very short flight one motor quit work an Prop was standing sitll...
I was glad to see, that autoquad can handle such an issue, because my octo was still flying, level
and I landed safely.

But anyway im not really happy...
Next step i try to improve the PI settings of the ESC´s
and I will update FC to Firmware 6.7

Is anyone out there who can say something about the vibrations? (see first Post)

bye
Marco

[chschmid]

[url]PI default setting needs adjustment, due to Motors wont really start.[/url]
Adjust the start voltage for that. Not the PI.

Cheers
Christof

[Marco]

hey Christof,

of course the start up voltage not the PI.


nice weekend
greets Marco