| Textile industry is a very important industry of people’s livelihood in China. As the yarn quality has a direct impact on the appearance quality of the fabric, it is very important to measure and evaluate the yarn evenness:(1)The structure characteristics and optical system of CCD are studied based on the edge characteristics of yarn detection model and yarn diameter. The CCD is used to segment the line array CCD, and the detection accuracy is increased from 56 μm to 10 μm based on the principle of linear array CCD.(2)The yarn diameter curve is measured by linear array CCD, and the slope threshold method is put forward based on the edge characteristics of yarn signal. The method of slope threshold method was proved to have the full feasibility of the yarn diameter by using three kinds of space function fitting method to study the change of gray value of yarn diameter. The factors that affect the accuracy and the speed of the slope threshold method are also studied, and the best fitting model for the on-line detection of the yarn is w=3,s=3, KT=45. The error of the measured value and theoretical value of the fitting model is proved to be within 3%, and the algorithm is verified by the experimental results.(3)The yarn diameter appearance measurement system is designed and developed and the sampling length of the constant sampling interval is obtained and the factors affecting the CV value of the yarn variation coefficient is analyzed. Through the analysis of the feed rate and the number of the yarn, it is concluded that there is little effect on the variation of the coefficient of variation. At the end of the experiment and simulation, the experimental results show that with the increase of the sample length, the coefficient of variation of the coefficient of variation is gradually reduced, the measured coefficient of variation of yarn with Uster 50% is at the same level in the sampling length. |
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