Abstract: On a warp-knitting machine with closed-loop controlled electronic let-off system, the warp let-off is often impacted by the speed change of the main shaft during turning-on and turning-off the machine, since the movement of beam lags behind that of main shaft, causing tension change of the warp. By testing the response performance of beam motor and analyzing the law of warp tension change, a compensation method was developed, which can significantly improve the stability of let-off tension during start/stop of warpknitting machine and consequently improve the quality of warp-knitted products.

Key words: warp knitting; electronic let-off system; closed-loop control; tension change; response performance