Re: [Emc-developers] Axis and Joint limits

[Frank Tkalcevic]

> Under what sort of circumstances would you have different axis and joint 
> limits? 

A robot arm will have joints and axis that completely different.



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Re: [Emc-developers] Axis and Joint limits

[Gene Heskett]

On Monday 12 October 2020 16:02:50 andy pugh wrote:

> I feel that this is the sort of question that I would expect to be
> answering, not asking, but...
>
> Under what sort of circumstances would you have different axis and
> joint limits? The INI config docs don't really say, and in fact use
> "axis" in the "joints" section to add to the confusion.
>
> I am trying to set my mll up with a manual B axis. I want to be able
> to tilt the head manually, then set the angle in the GUI (by jogging
> or MDI) and have the XZ plane rotate.

I've never done it by that description, but I've never had limits coming 
into play in an axis that has no rev limits. But this description seems 
to entail both A and B rotations, so even if one of these axises is 
manually tilted, it seems to me you need to set the B axis with at least 
a parameter imported from the .ini or by a pyvcp spin dial so that 
linuxcnc knows this tilt angle. Then, if using the correct kins, you'd 
at least have a troubleshootable test setup.

> This sort-of works, but I keep getting soft limit errors when the
> machine is nowhere near the physical joint limits.
>
> I am wondering what drawback there might be with simply expanding the
> axis limits.

That, to me would be spooky math, particularly no better than I am at the 
various transcendental's.

One of the things I expect to battle with is exactly this in configureing 
a BS-1 clone for use on the G0704, primarily because with a chuck 
mounted, tilting that head will at some tilt angles, be put the cutting 
tool higher than the head can reach. I should have bought a BS-0, and 
might have to yet.  But compared to a BS-1, a BS-0 is a toy.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-developers] Axis and Joint limits

[andy pugh]

On Mon, 12 Oct 2020 at 21:02, andy pugh  wrote:

> This sort-of works, but I keep getting soft limit errors when the
> machine is nowhere near the physical joint limits.

Part of this might be because I am using a non-identity kins declaring
as KINEMATICS_IDENTITY, but this was meant to be a minor tweak to a
machine that is set up for Touchy.
(And Touchy refuses to run with KINEMATCS_BOTH)

Well, the version of 2.8 I am running does, anyway. I probably should
update to the current release.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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[Emc-developers] Axis and Joint limits

[andy pugh]

I feel that this is the sort of question that I would expect to be
answering, not asking, but...

Under what sort of circumstances would you have different axis and
joint limits? The INI config docs don't really say, and in fact use
"axis" in the "joints" section to add to the confusion.

I am trying to set my mll up with a manual B axis. I want to be able
to tilt the head manually, then set the angle in the GUI (by jogging
or MDI) and have the XZ plane rotate.

This sort-of works, but I keep getting soft limit errors when the
machine is nowhere near the physical joint limits.

I am wondering what drawback there might be with simply expanding the
axis limits.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Re: [Emc-developers] reallytrivialkins

[Curtis Dutton]

Yes!

Another reason for this move would be to increase basic consistency within
the project.

I think it would be reasonable for a user of linuxcnc to expect that all
customizations that come "in the box" be buildable with halcompiler. Maybe
that isn't exactly possible right now but moving things in that direction
would be noble.

-Curt

On Sun, Oct 11, 2020 at 9:17 AM andy pugh  wrote:

> I wonder if it is worth adding a minimal kins to the project,
> basically the old hard-coded trivkins with a 1:1 mapping between the
> joints and axes.
> The intention would be that it could be pointed at when answering
> questions about custom kinematics as an example of a skeleton for a
> one-off kinematics file.
>
> Partly this is because the current trivkins does not compile with
> halcompile whereas the old trivialtrivkins does.
>
> --
> atp
> "A motorcycle is a bicycle with a pandemonium attachment and is
> designed for the especial use of mechanical geniuses, daredevils and
> lunatics."
> — George Fitch, Atlanta Constitution Newspaper, 1912
>
>
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