Can you take a look at this accelerometer measurement?

claustro

Hi guys,
I mounted an accelerometer on my c-bot
Board: Duet 2 WiFi (2WiFi)
Firmware: RepRapFirmware for Duet 2 WiFi/Ethernet 3.4.6 (2023-07-21)
Duet WiFi Server Version: 1.27
It seems to be working fine, I tried hand-shaking it for confirmation.
The " problem " is that it doesn't measure a real "peak" when mounted on my machine, al measurement seems coherent with each other so it seems fine
What should I do next? Where should I put the "peak" here?

Here is a video
https://youtu.be/3LwV5iQyo7M

Immagine 2024-01-22 102010.jpg

Thank you

oliof

@claustro you've either built a really rigid system and the speeds you are running the test at aren't conducive to vibration, or the accelerometer is not measuring the vibration close to the nozzle, or it's a highly dampened system where IS will be largely ineffective.

You could cross check your accelerometer measurements by printing a reference print (I like the https://marlinfw.org/tools/input_shaping/freq-calibr.html because it's a direct read off of a single layer print) to see if you get wildly different results.

claustro

@oliof Thank you for your answer.

My firmware movement speeds are

M350 X16 Y16 Z16 E16 I1                        ; configure microstepping with interpolation
M92 X100.00 Y100.00 Z1000.00 E412.00           ; set steps per mm
M566 X600.00 Y600.00 Z300.00 E1200.00          ; set maximum instantaneous speed changes (mm/min)
M203 X15000.00 Y15000.00 Z300.00 E1200.00      ; set maximum speeds (mm/min)
M201 X3000.00 Y3000.00 Z400.00 E4000.00        ; set accelerations (mm/s^2)
M906 X1200 Y1200 Z1300 E800 I30                ; set motor currents (mA) and motor idle factor in per cent

Increasing the acceleration from 1500 to 3000 I obtained this accelerometer pattern

I run the test you pointed me out but I don't know if I settled up correctly.

This is the result

pattern 3.jpg

Now I am stuck

Thank you
Andrea

l

oliof

@claustro maybe @tombrazier can help us with this one (-:

oliof

@claustro you set the acceleration to 500 in the generator. You should set it to 3000 for comparability (and make sure that the acceleration is set with RRF compatible syntax).

tombrazier

@claustro I think the image of the calibration pattern is rotated 90°. Assuming that is correct then the Y calibration is the line on the left and the X calibration is the line on the bottom.

It looks like there is pretty much no resonant frequency in the range 0Hz to 90Hz for Y and the X resonant frequency is about 4/5 of the way along the line at just over 70Hz.

Important question: was input shaping disabled when you ran the test?