An innovative device for bobbin thread consumption measurement on industrial lockstitch sewing machines

This paper presents some development work following up on previous research on monitoring and control techniques for high-speed industrial sewing machines. The main objective of the studies is to develop techniques and devices to allow a faster set-up, greater flexibility and higher product quality in industrial sewing operations. One of the main aspects of the sewing process is the interlacing of threads-stitch formation. It has been found that the on-line measurement of thread consumption can provide information about stitch adjustment and serve as a feedback variable for thread tension control. In this paper, an overview of this technique will be given, with particular focus on the quantification of bobbin thread consumption in lockstitch machines, one of the most widely used type of machine. In this specific case, measurement is difficult due to lack of physical space for the sensors.