David Branscomb

Fault detection in braiding utilizing low‐cost USB machine vision

This paper investigates the effect of yarn tension on braid formation point (braid point) motion. A computer‐controlled take‐up machine is developed to facilitate braiding experiments. The results of several experiments are used to recognize tension aberrations that lead to poor quality and wasted product. Optimal braid performance is observed, which serves as the baseline for comparing the behavior of faults. By studying the effects of common faults, a diagnostic tool is developed to recognize the onset of defects and provide some insight into what might be causing the fault. Radial fluctuation of braid point position is a good indicator of mechanical faults of the tensioning mechanisms. Observations based on mechanical and visual methods are also presented as diagnostic tools. From visual observations, it can be concluded that as the tension in one yarn increases with each revolution, the radial fluctuation increases until a yarn breaks. From mechanical observations, it can be concluded that the fluctuation in motor speed increases until the point when the yarn breaks. Through this study, braid point motion can be used as a diagnostic for shutting down the machine before irreversible damage occurs.

On the dispersion property of a plain-weave textile metamaterial

Applications of textile material in electromagnetics have been an active research area in the past decade. Numerous researches of antennas and other electromagnetic structures based on textile metamaterials have been presented. However, not much in-depth study of the impact of the periodic nature of textiles on electromagnetic band gap (EBG) properties has been done. In this study, a planar artificial magnetic conductor (AMC) / artificial electric conductor (AEC) grating structure and a conductive/nonconductive textile EBG structure are modeled and analyzed using the CST Microwave Studio eigenmode Jacobi-Davidson (JDM) method. The AMC/AEC grating and the textile EBG models have the same design parameters, but the dispersion results show that the periodic nature of the textile structure is able to split the TM/TE band and creates a bandgap for the X to M wave vectors. As a result, by introducing a plain weave structure, the AMC/AEC grating is transformed from a 1D EBG into a 2D EBG structure. A distributed parameter transmission line model is also presented to explain such phenomenon. This study presents the first discussion on textile induced EBG and suggests further development on textile based metamaterials.

Geotextile–microstrip–hybrid antennas for roadbed based wireless communication

Incorporating microstrip antennas (MSAs) into geotextile materials is a promising alternative to utilize advanced wireless capabilities such as wireless traffic monitoring into public transportation infrastructures. Together with a reference MSA, three geotextile–microstrip–hybrid antennas (GA) with different plain weave configurations were fabricated. Full-wave simulation and experimental results confirm that the fabric pattern of the GA affects its radiation characteristics. The dominant TM010x mode of MSA is disturbed by placing conductive wires in the weft direction only. Meanwhile, a higher order TM002x mode exists and yields radiation patterns more suitable for roadbed-based wireless communication application. This suggests that it is possible to manipulate the radiation characteristic of a GA by controlling its weaving configuration. A preliminary package error rate test is also performed and the feasibility of using the GA as complimentary wireless communication hardware is discussed.

Application of Machine Vision Techniques for Fault Diagnostics and System Examination of Braid

Important factors of braid formation are yarn motion, yarn tension and intra-yarn frictional forces. In order to improve quality of braided structures the effects of yarn tension and resulting braid formation position must be understood and controlled. This paper reports the effect of yarn tension on braid formation (braid point) motion along with the radial and longitudinal motion of the braid point in the initial, transient, and final positions. Visual observations utilizing low cost webcams are also presented as well as a diagnostic tool which can recognize the onset of defects and provide some insight into what might be causing the fault. Optimal braid performance is observed which serves as the baseline for comparing the behavior of faults. Radial fluctuation of braid point position is a good indicator of mechanical faults of the tensioning mechanisms. The experiments performed will provide the foundation for further work with applications for improving braiding quality in ropes, tethers, and structural composites. Finally, this experimental study and dynamic characterization will be useful for assessing future passive and active control methods, along with sensing.Copyright