Yarn velocity measurement using optical correlation method

Abstract

A high performance yarn speedometer adopting optical correlation method has been developed to contribute to efficient improvement of looms. Among some velocity measuring methods, optical correlation method is the most suitable for a yarn intense speedometer because of its high accuracy and simple equipment composition. Optical characteristics of spinning yarn and filament yarn were investigated for the development. The investigation of frequency characteristics revealed that transmitted light intense signals for both the yarns were roughly random, which indicates optical correlation method was suitable for velocity measurement. Measuring accuracy of a trial manufacture yarn speedometer was checked by measuring the velocity of the yarn which moved at a constant velocity. The influence of the structural factors of the trial yarn speedometer on the accuracy was also examined. Based on the above result, the trial yarn speedometer was adjusted optimally and the yarn velocity near the main nozzle of air jet loom was measured. The measuring accuracy of the adjusted speedometer was found comparable to that of laser Doppler velocimeter.