Velocity problems

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22 Aug 2013 11:47 #37948 by eslavko
Replied by eslavko on topic Velocity problems

Regarding auto and mdi modes, 5 axis programs are normally written in inverse timing mode, which gives more control over the machine by the program. This adds to the dificulty of making one by hand. However, it is not so hard to write a script which takes as an input the almost finished gcode file, and outputs the finished gcode file whith the correct feeds in order to keep the machine working at maximum speed within it´s constraints. This way, you can work within both axis and joint constraints, without having to lower the axis constraints so that joint constraints are honored even in the worst case scenario.

Hope I made myself clear, I've tried to use the specific vocabulary
Lisandro


Hello...
Well that part of message is not clear for me. I don't understand what you mean with inverse timing mode, and what your CAM produces for output. Does macnine need 5 axis kins or all that is in CAM module and machine run with trivkins (like joint mode?)

I also thinking to preprocess G code to check if I have somewhere speed problem and correct feedrate acordingly. This should be trivial for G1 but what to do with G0? To replace all G0 with B or C axis to G1 and apply fedrate?

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22 Aug 2013 18:13 #37959 by lisandromassera
Replied by lisandromassera on topic Velocity problems
By inverse timing mode I mean using G93 instead of G94. See linuxcnc.org/docs/html/gcode/gcode.html#sec:G93-G94-G95-Mode
My machine uses the 5 axis kins. I don´t use a CAM. I use this machine to trim thermoformed plastic parts, and to make the programs I manually pick the points of the program and then use a script to calculate the feed.
I don´t use G0, I use G1 with faster feed.

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22 Aug 2013 22:37 #37975 by eslavko
Replied by eslavko on topic Velocity problems
Ok I understand (barely) now.

As I'm today connected my pendant and finished userspace component for it, I do 1'st jogs. It works nice. no joint follow error as I can jog it only in joint mode! In world mode all thing is death. (thus I can jog with cursor keys) What the heck....

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23 Aug 2013 19:19 #37998 by andypugh
Replied by andypugh on topic Velocity problems

In world mode all thing is death. (thus I can jog with cursor keys) What the heck....


Can you elaborate on what the problem is?

What pins does your jog pendant connect to?

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24 Aug 2013 12:54 #38024 by eslavko
Replied by eslavko on topic Velocity problems

Can you elaborate on what the problem is?

What pins does your jog pendant connect to?


Ok. Here is part of hal file with connection to pendant
#connect jog encoder whell to inputs
net     jogencoder	    axis.0.jog-counts	CaaJog.encoder
net     jogencoder	    axis.1.jog-counts	
net     jogencoder	    axis.2.jog-counts	
net     jogencoder	    axis.4.jog-counts	
net     jogencoder	    axis.5.jog-counts	

#whell is enabled only if axis key is pressed too
net     jogxen	            axis.0.jog-enable	CaaJog.x
net     jogyen	            axis.1.jog-enable	CaaJog.y
net     jogzen	            axis.2.jog-enable	CaaJog.z
net     jogben	            axis.4.jog-enable	CaaJog.b
net     jogcen	            axis.5.jog-enable	CaaJog.c

#connect correct scale signals
net     jog-lin	            axis.0.jog-scale	CaaJog.jog-linear-speed
net     jog-lin	            axis.1.jog-scale	
net     jog-lin	            axis.2.jog-scale	
net     jog-ang	            axis.4.jog-scale	CaaJog.jog-angular-speed
net     jog-ang	            axis.5.jog-scale	

The problem is that I can't jog machine when I'm in world mode.
When I'm in joint mode anything works ok. But when i switch to world mode (press $ key) the jog pendant doesn't work any more, but cursor keys on keyboard work.
If I use trivkins instead 5axiskins then jog does work as should in world mode.

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24 Aug 2013 18:01 #38028 by eslavko
Replied by eslavko on topic Velocity problems
Yet another problem with 5axis kins...

Exceeded negative soft limit on joint 0.


I didn't try on simulator but on machine the procedure is:

Start machine.
home all axis
press shift right arrow to quick jog X+
press shift left arrow to quick jig X-
-it's ok....
now go to world mode (press $)
press shift right arrow to quick jog X+
press shift left arrow to quick jig X-
error trip. The value on DRO is -14.9 but limit is set to -1 max!

seems that linuxcnc is so buggy with 5axiskins module that seems to be best to avoid it on real machine. :ohmy:

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24 Aug 2013 23:14 #38034 by andypugh
Replied by andypugh on topic Velocity problems

The problem is that I can't jog machine when I'm in world mode.


From the mailing list.
"Wheel jogging in WORLD mode is not implemented - micges thinks he
implemented this once already but the code is unfortunately lost. I
think he is looking for it."

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24 Aug 2013 23:17 #38035 by andypugh
Replied by andypugh on topic Velocity problems

seems that linuxcnc is so buggy with 5axiskins module that seems to be best to avoid it on real machine.


As I have repeatedly said, complex kins are known to be buggy in the normal released version. This is because the changes needed to make it work break existing configurations, and we avoid making such changes between major releases.

Joints_axes3 does avoid the soft limits.

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25 Aug 2013 01:17 #38037 by eslavko
Replied by eslavko on topic Velocity problems
Does someone know when next release should be published?

Does 2.6~pre have that issue's too?

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25 Aug 2013 01:46 #38038 by andypugh
Replied by andypugh on topic Velocity problems

Does 2.6~pre have that issue's too?


There isn't technically a 2.6 yet. The problem is still in "master".

There is some chance that when the release-candidate for 2.6 is created then the ja3 changes will be merged in.

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