On 12/26/2013 10:17 AM, Chris Radek wrote:
> On Thu, Dec 26, 2013 at 09:17:18AM -0600, Charles Steinkuehler wrote:
> 
>> simple "move the joint until the switch closes".  IMHO there needs to be
>> a way to write programmable homing routines that can perform coordinated
>> motion in joint and/or world space, But one thing at a time...
> 
> I don't see how you can possibly move in world space before homing.
> I do see how you could move all joints simultaneously, for instance,
> which might be what you mean?  This is a form of "coordinated"
> motion but it is not how we usually use the term "coordinated",
> which means in world mode and in lines and arcs, etc.
> 
>> PROPOSAL:
>> It seems to me that the limit check functions should be plug-able, like
>> the kinematics module.  The limits could then be as simple or complex as
>> required by any particular machine.
> 
> Have you tried just having your inverse kins return a failure in the
> situations you've identified as bad?  in JA4 this is dealt with
> nicely I think.  Endpoints are checked before a move is started.
> Not sure about how world mode jogs handle it.

I've had kinematics return invalid results for position, and I suppose
it behaves similar to hitting a limit (the machine shuts off and an
error is presented on-screen).  So position might not be too bad as-is
(although it's nice to be told if gcode exceeds the machine limits on
program load instead of 90% of the way through!).

I'm more concerned about being able to set coordinated acceleration and
velocity limits, so I can avoid having to perform X and Y moves at 57 %
of my available max velocity and acceleration just so the occasional XYZ
move doesn't exceed 100% of machine limits.

Details:
Given a maximum X, Y, and Z velocity of 1.0, the maximum speed of an XY
move is 1.414 (or SQRT(2)), and the maximum speed of an XYZ move is 1.73
(or SQRT(3)), so I have to set my limits to 1/1.73 (0.577) of the actual
limits or the machine will exceed them in the "corner" case.
(pun intended)

...or is there already a way to limit the "directional" speed and
acceleration of the head and not just the maximums in each Cartesian
coordinate?

-- 
Charles Steinkuehler
[email protected]

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