Knitting machines have an array of needles, each holding an individual knitting stitch. When a carriage passes over a needle it creates a new stitch. (This process being about 100 times faster than hand knitting.)
In tubular knitting machines, carriages move on a circular rail, while in flat knitting, carriages move back and forth, chainging directions after each row.
Although having to go back and forth is a backdraw, since it decrases knitting speed, and exceeds more stress on the machine, flat bed knitting machines have become extremly popular, in applications where flexiblity in shaping is required.
By using two needle beds facing each other, tubular structures of arbitrary diameter can be created. Moreover the diameters may change, and tubular structures may join, divert, start or finish, giving rise to arbitrary 3d structures.
The patterns of machine knitted fabric used to be limited by some kind of maximum pattern repeat, very much like the patterns created on shaft looms in weaving. But these times have been overcome. Automatic knitting machines let the user control every single stitch, and very much like the Jaquard-Loom, have made it possible to combine the efficency and speed of mass production with the detailed pattern control of handcrafting.
These possibilities have not been exploited to date, although it is evident that using fully fashioned knitting machines for mass production, is very much like using quantum computers for word processing.