Purpose

Devices for step estimation are body-worn devices used to compute steps taken and/or distance covered by the user. Even though textiles or clothing are foremost to come to mind in terms of articles meant to be worn, their prominence among devices and systems meant for cadence is overshadowed by electronic products such as accelerometers, wristbands and smart phones. Athletes and sports enthusiasts using knee sleeves should be able to track their performances and monitor workout progress without the need to carry other devices with no direct sport utility, such as wristbands and wearable accelerometers. The purpose of this study thus is to contribute to the broad area of wearable devices for cadence application by developing a cheap but effective and efficient stride measurement system based on a knee sleeve.

Design/methodology/approach

A textile strain sensor is designed by weft knitting silver-plated nylon yarn together with nylon DTY and covered elastic yarn using a 1 × 1 rib structure. The area occupied by the silver-plated yarn within the structure served as the strain sensor. It worked such that, upon being subjected to stress, the electrical resistance of the sensor increases and in turn, is restored when the stress is removed. The strip with the sensor is knitted separately and subsequently sewn to the knee sleeve. The knee sleeve is then connected to a custom-made signal acquisition and processing system. A volunteer was employed for a wearer trial.

Findings

Experimental results establish that the number of strides taken by the wearer can easily be correlated to the knee flexion and extension cycles of the wearer. The number of peaks computed by the signal acquisition and processing system is therefore counted to represent stride per minute. Therefore, the sensor is able to effectively count the number of strides taken by the user per minute. The coefficient of variation of over-ground test results yielded 0.03%, and stair climbing also obtained 0.14%, an indication of very high sensor repeatability.

Research limitations/implications

The study was conducted using limited number of volunteers for the wearer trials.

Practical implications

By embedding textile piezoresistive sensors in some specific garments and or accessories, physical activity such as gait and its related data can be effectively measured.

Originality/value

To the best of our knowledge, this is the first application of piezoresistive sensing in the knee sleeve for stride estimation. Also, this study establishes that it is possible to attach (sew) already-knit textile strain sensors to apparel to effectuate smart functionality.

中文翻译：

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基于压阻应变传感步幅估计的智能护膝研究

目的

用于步数估计的设备是用于计算用户所采取的步数和/或所走距离的穿戴式设备。尽管人们首先想到的是可穿戴物品，但它们在节奏设备和系统中的重要性却被加速计、腕带和智能手机等电子产品所掩盖。使用护膝的运动员和运动爱好者应该能够跟踪他们的表现并监控锻炼进度，而无需携带其他没有直接运动用途的设备，例如腕带和可穿戴加速度计。因此，本研究的目的是通过开发一种廉价但有效且高效的基于膝套的步幅测量系统，为步频应​​用的可穿戴设备的广泛领域做出贡献。

设计/方法论/途径

采用镀银尼龙丝与尼龙DTY和包覆弹力丝一起纬编，采用1×1罗纹结构设计了一种纺织应变传感器。结构内镀银纱线占据的区域用作应变传感器。它的工作原理是，在受到压力时，传感器的电阻会增加，而当压力消除时，电阻又会恢复。带有传感器的条带单独编织，然后缝到膝套上。然后将膝套连接到定制的信号采集和处理系统。一名志愿者受雇进行佩戴者试验。

发现

实验结果表明，佩戴者的步数可以很容易地与佩戴者的膝盖弯曲和伸展周期相关联。因此，对信号采集和处理系统计算出的峰值数量进行计数，以表示每分钟的步幅。因此，传感器能够有效地计算用户每分钟迈出的步数。地面测试结果的变异系数为 0.03%，爬楼梯的变异系数也为 0.14%，这表明传感器的重复性非常高。

研究局限性/影响

该研究使用有限数量的志愿者进行佩戴者试验。

实际影响

通过在一些特定的服装和/或配件中嵌入纺织压阻传感器，可以有效地测量步态等身体活动及其相关数据。

原创性/价值

据我们所知，这是压阻传感在膝套中用于步幅估计的首次应用。此外，这项研究还表明，可以将已编织的纺织品应变传感器连接（缝制）到服装上以实现智能功能。