On-Line Discrimination of Defect Type and Size of Knitted Fabrics by Narrow Band Eliminating Spatial Filtering Method

Abstract

A narrow band eliminating spatial filtering method has been proposed for the on-line defect detection of knitted fabrics. The defects to be detected have several types of defects to be classified. The defects caused by some troubles of the knitting machine give a serious damage on the whole fabrics. Some of the other defects occured by occasional irregularity of the knitting thread give a few temporal damages. For high quality control and high performance manufacturing, it is required not only to detect the defects but also to discriminate the type of defects simultaneously.
This paper describes how to discriminate the type and the size of the defects by using a pair of narrow band eliminating spatial filters. One spatial filter is set perpendicularly, the other is set in an inclined angle. This arrangement of the spatial filters realizes anisotropic signal processing.
The type of defects is discriminated by the anisotropic signal processing, and the size of defects is extracted from the zero-cross width of the output signals of the two spatial filters. The effectiveness of the proposed method is confirmed by computer simulations and experimentally evaluated.