Jack,

There is .c file called genhexkins in which the kinematics of a hexapod
(stewart platform is implemented). I think that hexapod is one of the
examples. I remember I started from that example to configure my own
hexaglide type hexapod. 

That file should be used as a template to start with.

There is also a puma robot example in which the same philosophy is used,
don'' remember the name of the associated kinematics module.

A minimum implementation would use only the inverse kinematics, if you
want a feedback of the cartesian coordinates based on joint coordinates
(instead of seeing commanded values) you should implement the direct
kinematics.

As I remember there is a couple of variables in the file with which you
choose if you are only going to use the the inverse kinematics or both.

In your emc configuration file (.hal) you'll have to load that
kinematics instead of the standard one (trivkins).

You will have to compile the module also.

I use a distribution compiled with "run in place" (./configure
--enable-run-in-place or something like this look for options), and
whenever I change the file a "make" suffices for this.

I have implemented the kinematics for this:
http://www.imac.unavarra.es/~cnc


If you are curious I can send you my config and genhexkins files.

If you know about kinematics is easy, you have linear equation solver
and a newton-raphson solver based on it within the genhexkins so
implementation is easy.

My emc version is pretty old but I think that in this side things are
more or less unchanged.

A problem I had to fight with (there was a bang in my initial setup) was
that the coordinates corresponding to the initial values (or may be
values after homing) of the joint and cartesian coordinates should
correspond to each other, I don't remember well but this problem was
related probably to the inverse kinematics.

As kinematics models can be complex I suggest that you debug your
kinematics off line until you get something that you think is OK.


Cheers,

Javier

On Thu, 2010-12-16 at 11:09 -0600, Jack Coats wrote:
> Could someone point me to where I can read on setting up the kinematics
> for a non-euclidean device (something more like a hexapod
> or Stewart platform
> rather than a gantry router).
> 
> This is just for my education, no specific use ... yet :)
> 
> I did try to read the manuals, but my understanding was not up to their
> level
> of description about how to do it.
> 
> Something like setting up a SCADA arm would be interesting to me, and should
> be simple compared to a hexapod/Stewart table.
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