On-line Loom Weft Density Control System Design

Abstract

Controlling the weft density in the course of weaving is of great importance in technical textiles production. In this study, a closed loop control system was designed and implemented in a weaving machine. Moreover, a PID algorithm was used in the control system. The control action starts by taking a picture from the fabric near the cloth fell. A machine vision system was prepared to calculate the number of weft yarns per inch. Based on the measured weft density, the take-up roller speed was adjusted by changing the supply voltage to the take-up motor. Because of the variable delay between the weft density measurement and cloth fell, the normal PID control system was not able to provide a robust action, and thus, a Smith predictor was utilized to modify the control behavior. The results of set point tracing and regulatory control action indicated the satisfactory performance of our novel system in various tests.