Sewing machine for joining two layers with different elongation - using two computers to calculate cross- and auto-correlation functions

摘要

A sewing machine for sewing together to equal length two layers of material with different elongation has two cameras to take partly overlapping pictures of each layer for temporary digitised storage. The correlation max. is determined by calculating the cross-correlation function of the overlapping picture signals. The actual elongation of each layer is determined by calculating the auto-correlation function. If neither the warp nor the weft threads run parallel to the direction of advance, their angle is first determined. A comparison of the advance parameters and of the elongations for both layers yields a control signal for the stitch positioner. ADVANTAGE - This sews together two layers of material with the same number of meshes or threads per unit length.