| The computerized flat knitting machine is a kind of double needle bed weft knitting machinery,it incorporates many subjects such as computer technology, mechanical design, electronic drives,knitting process and software engineering, so it is a typical electromechanical product. It is suitablefor producing cotton, wool, linen, silk, wool, and all kinds of chemical fiber. In recent years, withthe development of electronic science and technology, people start to pursue knitting clothing whichis fashion, comfortable, personalized and diversification. This trend promote the development of thecomputerized flat knitting machine. The market demand of computerized flat knitting machine isincreasing. By a late start of the knitting machine, there is still a big gap between domestic andabroad, so the study of the computerized flat knitting machine control system is very hot in recentyears. This paper is focused on the research of the control system of the computerized flat knittingmachine, a architecture and hardware platform of the control system is proposed. In addition, amethod of yarn tension control of knitting machine in FPGA is proposed in this paper.This paper first analyzes the development background and research status of thecomputerized flat knitting machine at home and abroad. Then the domestic and foreign literaturesare summarized, and the content and the meaning of this research is described. On the basic ofanalyzing the mechanical structure and working principle of the computerized flat knittingmachine, the basic knitting weaving process is described in detail. By the analysis of therequirements of the control system, a control system based on ARM9 micro processor and FPGAis proposed. It is designed by adopting the operating system of eCos and has a design ofhierarchical structure. The control system is composed of the main part and the head part, whichare communicated via CAN bus. The third chapter is about the hardware design of the controlsystem, which includes the peripheral circuit design around the ARM9 processor and the headcontrol system based on FPGA. The head control part includes solenoid drive circuit, needleselector drive circuit and stepper motor drive circuit. Freescale’s ARM9-based chip I.MX258 isselected as the processor of the main control part, and Altera’s FPGA chip EP1K50 is selected asthe coprocessor. The coprocessor is mainly used to control the external solenoid, motor andsynchronous signal. Instructions are issued by the main processor according to the signalsrequired by the pattern documents. So the weaving components can complete the specificweaving movements automatically. Based on chapter three, the PCB of the control system isdesigned, and signal integrity simulation such as overshoot, crosstalk and radiation of signals areimplemented by the software HyperLynx for the core circuit board of the control system, which can ensure the stability of the hardware platform. Finally, fuzzy control theory is applied to theyarn tension control of knitting machine. In this paper, parameter self-setting fuzzy PID controlmethod and a new technical method about real-time control of yarn tension is proposed. Firstly,simulation model is created with software Matlab/Simulink and is compared with the traditionalPID control. Then in the Quartus II development environment, parameters self-tuning fuzzy PIDcontroller, under the control of yarn tension, is constructed by combining principle diagram andVHDL design. At last realizing method in the FPGA is analyzed. The input data is tested, and theresults showed that design of the top-level circuit is stable and reliable, and it can be used for theyarn tension control of the computerized flat knitting machine.This system not only enhanced the practical applicability, but also has raised the level ofcircuit integration, and reduced the cost of the design. |
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