Pixracer second accelerometer vibrations can cause altitude rise?

ArduCopter Copter 3.5
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1

very interesting log part

image.png1667×536 189 KB

Vibration on the second accelerometer is much stronger then on second.
Can this vibration cause uncommanded altitude drift?
Where i can see which accelerometer commanded “rise up”?
set accel filtering to 10hz. This settings apply to all accelerometers?

2017-06-04 20-03-15.bin (2.3 MB)
also this setting
“INS_ACC_BODYFIX”

image.png799×47 2.05 KB

Set it to less noiser accelerometer can help?

2

add dampers
before

image.png1624×534 229 KB

after
image.png1643×535 225 KB

vibrations are smaller, but still clipping.
why?
vibes ±1.5 on noiser accel
image.png1638×544 196 KB

but why clipping rises?
2017-06-05 18-36-01.bin (2.2 MB)
with dapmers.bin (2.4 MB)

3

also

image.png1741×410 6.96 KB

PI show nothing

4

I had this pattern when it was mounted with self sticking foam and since I installed it on a damping platform its flying smoothly.

1 Like
5

i agree, FC need to be soft mountd. I use O-rings, but vibrations still not good. Try soft mount motors - still not good.

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last flight
2017-06-08 20-23-20.bin (795.2 KB)
i not have altitude rise in this flight, but strange
PI - Index showing which instance of EKF2 has been selected for flight control
But my logs have blank graph

6

Alexey,

Thanks for testing and reporting back.

The vibe levels in your last log look totally fine. All below 20m/s/s which is within tolerances (less than 30m/s/s is “acceptable”, 30~60m/s/s is the “grey zone”, above 60m/s/s is definitely bad). You shouldn’t see altitude hold problems at this level.

There are just 3 clipping events which is also nothing to worry about. Maybe it got a momentary whack as it hit the ground or something but in any case, 3 is nothing to worry about. 300, that’s trouble but 3… no problem I think.

1 Like
7

thanks!
There is nothing suspicious that the graph PI is empty?

image.png1741×410 6.96 KB

8

I must admit I rarely look at the EKF/NKF messages. I only dig into them if something else looks odd in the main vehicle logging. We’ve done some updating of the EKF description and I think @priseborough plans to update the EKF wiki pages more. … perhaps we can add some descriptions of those log messages.