Re: EMC Problem

Jon Anderson wrote:

> From: Jon Anderson <janders@...>
>
> Ian Wright wrote:
>
> > I haven't yet worked out how they are better than conventional
> > tools.
>
> Hexapod's structural integrity is derived from the fact that elements
> that comprise the equivalent of XYZ slides on a conventional machine are
> either in tension or compression.
> Once the screws on the 6 "legs" are calibrated, all machine accuracy is
> derived from mathematics.
> Controlling one with EMC would be interesting.

Already done. EMC was designed from the ground up to handle machines
of various construction, especially robots, with multiple, stacked rotary
joints. So, it has both forward and reverse kinematics routines to convert
from cartesian to machine axes and back again. There are several hexapods
being run under EMC right now, and more on the way.

> EMC, and any other
> conventional CNC program, assumes an axis move means controlling one
> motor and monitering velocity and distance.

No, for EMC, a simple 3 orthogonal axis machine is just a degenerate
case of the kinematics.

> With a hexapod, something has to take that single axis move and perform
> a lot of trig calculations. Contouring just makes things more
> interesting. Adding additional axis at the workhead allowing
> reorientation of the spindle would really add to the fun!

Yup, the trig gets complicated.

Jon