By now all modern weaving machines use integrated electronic systems which are operated by the
drive and control unit of the machine. The warp beam and the take-up motions are driven by high
precision servomotors equipped with speed reducer, connected with the machine’s PLC through an
encoder (a kind of electronic goniometer) and controlled through a closed adjustment ring. This
ensures the synchronization of the weaving machine with the let-off and take-up motions
(operating in series): practically the controller can know at any moment the exact position of the
various devices.
A position sensor or a load cell signals at any moment the tension operating on the back rest roller
and permits to adjust the let-off speed so that the tension remains absolutely constant from the start
to the end of the weaving cycle. Furthermore the positions of the take-up and let-off motions
during the critical starting phases can be adjusted to the running behavior of the material in
progress, in order to avoid stripes on the fabric. Also the weft density can be varied without
limitations during weaving and it is also possible to modify the warp tension by means of a simple
keying in.