Online Friction Measurement and Wear-Life Determination for Textile Needle Hooks Based on Closed-Loop Tension Control and the Capstan Model.

This paper proposes an online wear monitoring and lifetime assessment method for textile needle hooks, based on yarn tension sensing, closed-loop tension control, and the capstan model. The yarn tensions on both sides of the yarn-needle wrap interface are measured in real time and used to estimate an equivalent friction coefficient, which serves as the monitoring index for wear evolution. Closed-loop average-tension control was employed to reduce variability in operating conditions and enhance the consistency of friction coefficient estimation. To improve robustness, the signal-processing pipeline includes tension-floor gating, ratio clipping, missing-data handling, outlier rejection, pre-filtering, and post-filtered differentiation. Wear-life determination is achieved through a baseline-referenced criterion that combines a relative threshold with persistence time, defining the life endpoint as the earliest sustained deviation from the steady-stage baseline, rather than isolated spikes. Experiments conducted on needle hooks of different quality grades demonstrate that the proposed method yields stable yarn-tension measurements, enables clear discrimination among wear states, and produces wear-life assessments consistent with offline microscopy observations. The aforementioned method is computationally lightweight and suitable for practical online wear monitoring, thereby enabling data-driven timing of needle replacement in looms.