Maiden Quad Flight - Vibrations Help

Evening All,

Conducted a maiden the other day. Haven’t run through dynamics notch, autotune, etc. - just quick maiden to see how it handles before running into that stuff. I noticed that vibrations are relatively high - but even higher on IMU3. If I remember correctly - this is the IMU that is not damped within the Cube Orange. I am working on reducing vibrations as much as possible - but does it matter too much if the IMU3 has relatively high vibes if the other two are rock solid?

Bin Log:

What size props have you got?

You vibration levels should be acceptable but keep an eye on it. Anything you can do to reduce vibrations is good.
The GPS position was a bit off if anything, the HDOP and update rate is varying.
or GPS_GNSS_MODE,67 and see what works for best for you. Check GPA Delta (a nice straight line along 200ms is ideal) and GPD HDOP (lower is better).

You can see on the map the IMU calculated position and GPS position never agree.

For tuning start with these:
INS_HNTCH_ENABLE,1 ← set this then refresh params to see the rest
INS_HNTCH_REF,0 (this could be 0.16 after tests)
INS_HNTCH_FREQ,80 (I suspect this could be about 100 after tests)

If your props are about 18inches you should be able to use
Depending on your ESCs,
or MOT_THST_EXPO,0.5 for T-Motor Flame
Search for T-Motor Flame expo and come to your own conclusions :thinking: expo could be anything from 0.2 to around 0.4 to “normal” like 0.73

In that log it looks like your D term is a bit high.
I think you’d be able to safely try these PIDs, but as always be cautious with the first launch and land immediately if there’s too much instability

Send more logs :slight_smile:

Thanks xfacta - I was able to get the bird under control after a bit of troubleshooting. Turns out the vibrations were caused by a poorly mounted mock payload for flight testing.

The GPS behind the area you see there is not great - which is why you see the offset. When I move to a more open area the track is much better.

I added a notch filter - it has been a while and I no longer have the bird so I don’t remember what the final loadout was. I think it was around 100Hz (most of my aircraft at this scale that I use are around this).

IMU3 was still around 25% higher in vibrations - but everything was under 10 so I was happy with it.