2 motors for the same axis

Gloup
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11 Nov 2015 17:34 #65125 by Gloup

Replied by Gloup on topic 2 motors for the same axis

Hello,
When I launch Linux Cnc, on axis, I don't have X, Y, Z, but 0, 1, 2. I guess this is normal.
I can request an origin on all axis :

First Z, this is OK
Second X and X(A) : this is OK. Two axis stop on their own switch limit
Third, Y, this is OK

Then, when it finish, I switch using $. Now 0, 1, 2 are replaced by X, Y, ... and an error appeare. The exact message is "Erreur de suivi jointure 0". In english, the approximative translation is "error of following joint 0".

Thanks

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cncbasher
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11 Nov 2015 17:52 #65127 by cncbasher

Replied by cncbasher on topic 2 motors for the same axis

at least you managed to switch from world mode ,
look in your ini for the follow error values per axis and increase the min follow error to say 0.5

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andypugh
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11 Nov 2015 17:53 - 11 Nov 2015 17:54 #65128 by andypugh

Replied by andypugh on topic 2 motors for the same axis

Can you go into Machine->Show HAL config and check the Signals
xpos-cmd, xpos-fb
apos-cmd, apos-fb?

Last edit: 11 Nov 2015 17:54 by andypugh.

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andypugh
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11 Nov 2015 17:59 #65129 by andypugh

Replied by andypugh on topic 2 motors for the same axis

Looking here:

linuxcnc.org/docs/html/man/man9/gantrykins.9.html

I wonder what this means, in practice?

In the inverse kinematics, each joint gets the value of its corresponding axis. In the forward kinematics, each axis gets the value of the highest numbered corresponding joint. For example, with coordinates=XYYZ the Y axis position comes from joint 2, not joint 1.

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andypugh
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11 Nov 2015 18:07 #65130 by andypugh

Replied by andypugh on topic 2 motors for the same axis

andypugh wrote:
I wonder what this means, in practice?

This sort-of makes sense. There are two X-feedbacks from two (different) stepgens and only one can be compared to the internal X value.

Try short-circuiting the axis.0 feedback, like this: (ie comment out the stepgen and send the command back as feedback)

net xpos-cmd axis.0.motor-pos-cmd => stepgen.0.position-cmd
#net xpos-fb stepgen.0.position-fb => axis.0.motor-pos-fb
net xpos-cmd axis.0.motor-pos-fb

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Arro
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07 Feb 2020 10:01 #156688 by Arro

Replied by Arro on topic 2 motors for the same axis

Hi,

I have a similar problem with axis definition.
I was able to configure a tandem axis (X or Y) in "world-mode".
Now when I define a "tandem-axis" the system sets directly the "joint-mode" and I cannot set it back to world-mode with view-panel.

does anybody know about some wrong settings somewhere ?

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tommylight
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07 Feb 2020 11:09 #156693 by tommylight

Replied by tommylight on topic 2 motors for the same axis

Can you please attach the hal and ini files so we can have a look ?

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Arro
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07 Mar 2020 08:45 #159386 by Arro

Replied by Arro on topic 2 motors for the same axis

It has to do with the ohming

One time you perform the ohming for all axis the system turns into world-mode

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