Position error with encoder

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18 Aug 2021 11:26 #218065 by Aciera
Replied by Aciera on topic Position error with encoder
Ah I see. I find the encoder scale values quite odd.
What kind of linear encoders are you using?

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18 Aug 2021 11:57 #218066 by Messkid
Replied by Messkid on topic Position error with encoder
These are some magnetic linear encoders, and they are quite different, that's why I adjusted this parameter to find a good value and make sure that the measure on the CNC and in the real life are correct. For example i checked that a 10mm move on the X axis displayed on the screen is really a 10mm move.

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18 Aug 2021 12:27 #218067 by Roiki
Replied by Roiki on topic Position error with encoder
Can you give us the make and model of the encoders? It's possible you're losing steps on them at some point.

Do you have any rapid movements in the program? One way to check is to run a program without rapids and really slow feedrate and see if the problem persists.

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24 Aug 2021 11:58 #218619 by Messkid
Replied by Messkid on topic Position error with encoder
hi,
There are miniature encoders from POSIC with magnetic scale, I think I dialed them correctly, the encoder scale is good and i spend a lot of time checking for a mechanic issue, and now everything is good and secured.
But i keep having a following error up to .5mm during movements, this cause and issue when i'm probing a part and misalignement in general ..

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24 Aug 2021 17:44 #218630 by PCW
Replied by PCW on topic Position error with encoder
Did you try checking for encoder errors?

Are the encoder interfaces single ended or differential?

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25 Aug 2021 06:31 #218679 by Messkid
Replied by Messkid on topic Position error with encoder
I did, I checked a lot of things about the encoders and everything seems to be right about them. I'll post a screenshot of halscope to show the error.

Now i have a more precise move and it keeps a good origin, but the following error is just super important.and this cause and error when i'm probing.

I'm using the 2.8 LCNC, could this be an issue ?

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25 Aug 2021 14:09 #218706 by PCW
Replied by PCW on topic Position error with encoder
Now you don't have position loss but just following error during motion?
That's more likely a tuning issue (if you don't accumulate static position errors)

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30 Aug 2021 12:54 #219164 by Messkid
Replied by Messkid on topic Position error with encoder
Exactly, I gave up this week-end on this issue for my mental health, but i'll get to this point soon. I tried any PID tuning, tried to tune FF1, reduced speed.. i keep having a following error during motion on my axis.

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30 Aug 2021 17:40 #219179 by PCW
Replied by PCW on topic Position error with encoder
Can you post a screen shot of a halscope plot of the following error?

( plotting joint following error along with joint velocity is best for diagnostics )

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