Pulse frequency calculation and estimation in yarn evennessanalysis

摘要

The present paper describes work carried out, within a project tothe textile industry, to achieve supervision and characterization ofspun yarn. One of the main goals was to establish a methodology toeasily determinate the roller draft that causes irregularities. Twodifferent approaches to achieve decomposition of a binary signal indigital signals with known pulse frequencies are presented. The firstapproach, already used and tested in the laboratory, is based on twodifferent methods: the first method uses an accelerated algorithm basedeither on the Fourier or Walsh transforms, while the second one presentsa new methodology, DFI (impulse frequency determination), for signalswhere long periods with very short duty cycle are expected. The use ofone of these methods instead of the other depends on the characteristicsof the signals under analysis and on the pursued objectives. A newmethodology to decrease memory amount and increase the speed of the DFIcalculation is presented and discussed. Several techniques are compared.A new approach using logical analysis of the thresholded signal of theyarn mass, to establish the probability of a pulse frequency to be oneof the signal components, is under study at our lab