Very interresting work! Thanks for that!
I build a small CNC machine whose X and Y axis are replaced by linear arms pushing directly the spindle, in a "bipod" configuration. Stiffness and precision of the prototype are very impressive.
I am now working for a repstrap 3D printer declination, called "dipode" (open source project), which should be very simple, cheap, effective and outstandingly fast. I really think that this innovative non-cartesian machine could outperform any current repstrap, according to both cost, speed or precision, but I lack a good stand-alone electronics solution.
Today, these machines are drived (quite well) by emc2 / LinuxCNC running on an old laptop. Therefore, the step frequency limits the hardware speed.
As you probably know, emc2 uses a single c module to translate from cartesian space to machine's linear drives (direct kinematics and inverse kinematics). You claim that Smoothie is tailored to handle non-cartesian architecture. I am not very comfortable with the software environment, so I need an example to learn how to cope with the relevant module.
Thanks for your help!