DoN. Nichols wrote:



Non-Cartesian? -- You mean like the hexapod? I believe that was
one of the early experiments built around EMC (what LinuxCNC used to be
called.)
There's hexapods (Stewart platforms) and hexaglides, and 4- and 5-axis
machines, as well as robots and SCARA arms. There are also other schemes
that can be assembled from a combination of rotary and linear axes.

LinuxCNC can control all of these, although the more unusual ones
require writing some code. Also, this flexibility allows you to
correct for inaccuracies in the machine construction, as Stuart Stevenson
at MPM demonstrated with a 5-axis Cincinnatti mill in his shop.

The big difference between Mach and LinuxCNC in this are is LinuxCNC
can control all of these machines in Cartesian space, with standard
XYZ G-code, and let the kinematics routines figure out what crazy
angles the joints need to be in to reach each position. So, you can
even JOG a robot in Cartesian coords. Mach just treats all axes
as numbers, so you'd have to program all axes of a robot numerically.

Jon