Re: 6 axes

[Ray Henry <rehenry-at-up.net>]

Till

As far as 6dof, I think that EMC is only ready to think about more than
3dof for what is called a Stuart platform. (hexapod) Fred's recent post
suggested that they needed to do quite a bit of work on the motion planning
files before we could set up a,b,c as rotated around their respective axis.

I saw the big hexapod when I was at NIST this spring.  It's awesome.  I
also read the posts you saw that talked a bit about the tabletop model that
NIST used for a textbed this summer.  If I remember correctly, they used
cables of some sort to hang the spindle on.

I don't know how to set up the whole emc for it but you should read these
files.  They have the kinematics that are involved in Stuart platforms.
They should give you some idea of the range of the joint variables that you
can build into your machine.

	emc/src/genhexkins.c
	emc/src/genhexkins.h

The stuff necessary to make the motion control files for it are in the make
file in the same directory but I have no clue what they mean.  I can barely
read it and don't understand it at all.  Fred can give us a description on
how to compile an EMC for a hexapod.

There are six sets of stepper signals on the parallel port so that would be
easy.  I thought that there was a description of which pins were which on
the emcsoft page but didn't see it there the last time I visited.  My list
shows:

	DB25	Cent	Signal	
	1	1	mot-4 dir
	14	14	mot-4 clock
	2	2	mot-0 dir
	3	3	mot-0 clock
	4	4	mot-1 dir
	5	5	mot-1 clock
	6	6	mot-2 dir
	7	7	mot-2 clock
	8	8	mot-3 dir
	9	9	mot-3 clock
	16	31	mot-5 dir
	17	36	mot-5 clock 

You'll need to define the six axis in the ini file.  I believe that they
will all be linear and use common measurements.

You can also use the yemc gui directly to display six axis.  I'd suggest
that you modify the text size as I detailed in my recent post. (this should
be up in the cookbook in a couple days.)  Or I think that I can modify the
tkemc to show the same six axis display.

The next to last part that would have to be there is the RS274NGC
interpreter and Tom Kramer said that he'd have something ready in a month
or so.

The last part would be to learn how to program the monster to make good
pieces!   

Ray


At 01:00 PM 1/16/2000 -0500, till sprach:
>Hi all!
>I just found an Article about a NIST Hexapod wit 6 Axes. The Article is old,
>but they planned to use the EMC Controller. This reminded me to the fact
>that there was another Hexapod somewhere on the Homepages of NIST that WAS
>running with emc. At least it seemed so. The transformations are also there.
>So is it just a job of search and not research to make 6 Axes work? I
>soldered myself a card for 6 Steppers an i am planning to build a
>6DOF-Mechanism.