Aiming at the problems of current circular weft knitting machines of nonadjustable yarn tighters while coil weaving dice to undynamical stepless adjustment of the yarn amount, single coil size and uncontrallabe diameter of two ends of cylindrical fabric, the diameter of the fabric is not controllable from beginning to the end. In view of these problems, the study designed a control technology for active dynamical yarn feeding for, in which the quantity of yarn and the speed of servo motor could follow the position and speed of the spindle.The dynamic control system based on location and speed control was designed according to the weft knitting principle and the requirement of yarn delivery, which uses a ARM processor, a servo motor and a encoder of collecting needle position. The design of key hardware circuit, the implementation of software development, and the control method which according to the position and speed signal by the orthogonal coding pulse count the control technology were discussed as far as the control technology was concerned. The dynamic position following and speed following of the servo motor were realized. The test results show that the active yarnfeeding device realized by this control technology has many advantages, that the amount of yarn can be adjusted dynamically, the size of the coil can be changed, the tightness of yarn can be adjusted dynamically, and the diameter of cylindrical fabric is variable, which improved the appearance and body feeling of fabric.
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