Design of yarn tension self-adaptive control system on warp knitting machine

In order to realize the control of yarn dynamic tension, the warp knitting machine should be able to control the variation of tension values in different angles in one course during the knitting process. In view of the defects of controlling the let-off of warp beam, such as large yarn tension fluctuating and can’t accurately control the yarn tension at different angles within a course and so on, a specific kind of yarn tension self-adaptive control system on warp knitting machine has been developed. By analyzing the fluctuation of yarn tension combined with the looping mechanism motion law and process parameters of a warp knitting machine, the hardware and software platform of the system are designed; the velocity control strategy of the system is optimized; the quintic polynomial interpolation curve is calculated, and the double FIFO(first input first output) dynamic interpolation motion method is planned. Meanwhile, the self-adaptive control algorithm is designed to realize the self-adaptive control of yarn tension. From the analysis of the feedback yarn dynamic tension value curve and in comparison with the traditional let-off control system, the self-adaptive control system can reduce the yarn tension peak by at least 55.2% and the yarn tension fluctuation range by at least 51.6%. It is verified that the self-adaptive control system has an efficient performance of yarn dynamic tension regulation.