MEASUREMENT OF YARN VELOCITY IN TEXTILE MACHINES USING A NON-CONTACT TRACER METHOD

Abstract

The presented measurement method uses a tracer for measuring the transit time between two fixed points of known distance. For the marking static electric charge is used, which can be impressed by a corona discharge and detected with a capacitive detector. Since the yarn is an insulator, the charge does not move on its surface; therefore the tracer signal is not changed during the transit time. This means that the system is a pure dead-time system, and the transit time can be calculated by measuring the phase-shift between the two detectors. This phase shift is determined by a simplified Fourier-transform done by a microcomputer. This microcomputer is also used for generating all needed signals, input-output and averaging.