Research on the algorithm of precise positioning of the needle in computerized flat knitting machine based on CPLD

This paper presents an algorithm to real-time feedback the position of computerized flat knitting machine head based on AC servo motor in position mode. It describes the method that the state machine based on CPLD used to realize digital filtering and decoding for the orthogonal pulse produced by incremental photoelectric encoder. Then convert the results into the corresponding needle position, and feedback to the upper ARM system. It achieves the real-time and accurate positioning control of the computerized flat knitting machine head with this method. The proposed method has been the experimental test on computerized flat knitting machine, and achieved good control effect. This algorithm can be widely used in various industrial CNC systems.