Start this thread to have a place for focused discussion of the new vibration logging function of AC3.3. I'll start by copy-pasting my initial discussion from the AC3.3 beta testing thread.
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Rob, so how did you determine that the control difficulties stem from vibrations - FFT analysis?
I always check both the Accel values and the Vibes and use the one that looks worst as an indicator.
Basically experience told me. I could see the vibrations were high, and the thing was barely flying.
In the dataflash charts of IMU1/2, we see Z values commonly around -10, is this because the sensor chips are mounted upside down on the pcb and is capturing the 1g of earth's gravity? If so then is the Z axis a scale of 10, but x and y are scales of 1? Or are all axis g's x 10?
Zacc is around -9.81 since gravity is a downward acceleration.
Hi Group,
Is this thread still live?
Can you advise? -
Build - Quad-X Config Tarot 650S, Motor-4114, Prop 15.5 PixHawk FC FW333, (loaded ~ April 8th/2k16)
Batt 6S, Atun Success, MP 1.3.37
I have had this problem where plotting the Vibes Graph in MP I find that the X-axis appears ok,
whilst the Y-axis is 'way' diff to X.
I have inspected the rig to check for bad mechanics, all seems good.
Used diff sets of props of which I have balanced, imho
I am not experienced enough to eval the problem, I hope that within the community to find info
to assist resolving the perceived problem.
I have attached the bin file here for review as well as the various pics and Atun params.
When plotting the Des/Att Pitch & Roll, it appears to me the Att P&R follows the Des P&R closely?
Although I observe in Att P&R what appears to be a continuous ~sinosiodal-curve as it
tracks the Des P&R. Not sure is this is normal or acceptable?
The craft flies 'ok', however, since this is actually the first time for me in the uav tech,
I admit I am not experienced enough to evaluate the craft's 'practical' in the air
flight dynamics and performance. Although, in STBLZ mode it is quite 'agail' and 'responsive'.
In AltH and PosH it 'appears' to be good, as I understand it.
I am though concerned about the Vibes, I don't believe it is correct and may bite me on the 'bum' in the future if not sorted.
Lastly, note that I am not an experienced pilot at all.
I appreciate any feedback or pointers to help me resolve this, if possible.
Thank you for your time.
Regards,
Gerhard
Cape Town, South Africa
2016-05-13 16-28-40.bin
J1023.rar
Hi Julian,
Thanks for your reply.
Yes, it appears that way, vibration on the Y-Axis -
thus side-to-side and not Nose(Fwd)-to-Back?
btw, the Batt = 6S 8000mah
AUW = 3kg
Find pics of my build attached as compressed file.
Re build -
After viewing the build-pics -
The pic ..mountrubr2 indicates that -
The basemount-plate is mounted on the frame with 4x double-side square pieces of softrubber-double-sidedtaped. tape thickness : 10mm
You can then see the next plate (FC Carry plate) connected to the baseplate with 4xx anti-vibr rubber-bubbles.
The FC is mounted with 2 pieces 3M-d/side tape (~1.5mm thick) flat onto the Carry Plate.
Hope it makes sense?
If you need more info, please ask.
btw, I hate to jump around with the same topic into diff groups/threads, but initially I got no
feedback from the community. So, initially i posted here -
http://diydrones.com/forum/topics/vibe-xok-ybad-imu-problem?comment...
and here - http://diydrones.com/forum/topics/copter-3-3-beta-testing?commentId...
I will request in these 2 links to carry-on here so that all contributions can be on thread
Here is just a quick view of built -
DIY.rar
Gerhard, is this the common isolation mount and configuration being used for isolating the PH? If so, where can it be purchased? Link to a thread discussing this mounting method would be appreciated as well.
Thanks for posting pictures of your build....
Hi RichWest,
as far as I know the original and most probably best version of that mount comes from Guy McCaldin:
http://diydrones.com/profiles/blogs/3d-printed-anti-vibration-mount
The cheap plate/carbon versions as on Gerhard's copter deform the dampers - with unknown effects.
Thanks for the link, I searched after his reply and found the same thread as your link. It's a really interesting design, angled isolators. I had seen that design previously, but had no application for it at the time.
I would suspect in Gerhard's build that the isolators are resonating fairly well, not much absorbing being done as the isolators are in tension.
Again, thanks for the correction....
Hi Rich,
The double-mountplate with anti-vibration rubbers were supplied with the kit, when I bought it.
So unfortunately I can't recommend a supplier for the mount-kit alone, at this time.
Gerhard
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