[Al_The_Man]

This stuff has been around since the 70s!

But in different formats and methods, the original commercial systems used (uses) all in one proprietary co-processors for the HMI, CNC & PLC controllers.
Then came the PC based Motion cards such as Delta-Tau, Galil and Acroloop and the PC just provided the HMI, the cards closed the motion loop the same way the commercial systems do.
The method Mach uses is an HMI that also calculates the machine trajectory, this is then passed over to the motion drives via the P.P. Mach then relies on the stepper or in the case of servo's closed loop drives to complete the move.
IOW, there is no feedback to Mach (non-closed loop).
Al.