On 5/2/07, Eric H. Johnson <[EMAIL PROTECTED]> wrote:
Dirk,
> As far as I know hexapod code is in EMC2, but does it (still)
> work? Back in march there where some mails about it.
> Unfontunately there was no succes story follow up.
> Is there any way to test the hexapod code without building
> the real thing?
> How is the machinecode handled? I couldn't find anything
> about a hexapod postprocessor. Does EMC2 translate normal, 3,
> 4 or 5 axis code to something the hexapod can work with?
I asked about that a short time ago. I know someone that got a hexapod out
of a university lab and is looking for a control system, since they never
managed to get that part working sufficiently well. I have not heard
anything further as to whether he intended to proceed. Thus I don't have
any
further hands on experience.
At any rate, John K. responded as follows when I asked about hexapod
support:
"I'm sure it would not be a turnkey install.... but clever enough people
could certainly get it working. Things like homing will be the "fun"
parts.
Basic hexapod kinematics are in there, and were used back in the NIST
days.
They'd need some porting effort to interface with the newer motion
controller, but the tough math parts should be fine."
I can consider the "not a turnkey install" as a challenge.
As for the machine code, a hexapod uses the same G-Code as any other system.
What the G-Code coordinate system specifies is a point in space (Z, Y, Z)
and a tool orientation to get to that point in space (A, B, C). In simple
systems, the kinematics module trivkins (trivial kinematics) just does a
one
to one assignment between those coordinates and the associated axes.
Well, that is good news. No worry's about a complex postprocessor then.
There is a special kinematics module for hexapods named "genhexkins" which
does the translation between the spatial / orientation coordinates and the
axis orientation for a hexapod. For a simpler example of the principle,
look
at rotatekins, which simply takes a traditional 90 degree X/Y system and
rotates it 45 degrees. Thus in response to a command such as:
G1 X10 F50
Both the X axis and Y axis will move in equal amounts, resulting in a tool
path rotated 45 degrees from the direction of travel of the X and Y axes.
A
hexapod is just a more complicated version of this same principle.
Maybe something with 2 or 3 axis would be a good start. Like this tripod
that is mentioned in the linuxcnc wiki.
Dirk
-------------------------------------------------------------------------
This SF.net email is sponsored by DB2 Express
Download DB2 Express C - the FREE version of DB2 express and take
control of your XML. No limits. Just data. Click to get it now.
http://sourceforge.net/powerbar/db2/
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
