An Inductive Force Sensor for In-Shoe Plantar Normal and Shear Load Measurement
An Inductive Force Sensor for In-Shoe Plantar Normal and Shear Load Measurement
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DOI：
10.1109/jsen.2020.3006316
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发表时间：
2020-11
影响因子：
4.3
通讯作者：
Lefan Wang;Dominic Jones;G. Chapman;H. Siddle;D. Russell;A. Alazmani;P. Culmer
中科院分区：
文献类型：
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作者：
Lefan Wang;Dominic Jones;G. Chapman;H. Siddle;D. Russell;A. Alazmani;P. Culmer
糖尿病足溃疡（DFU）是一个严重的全球公共卫生问题。足底正常负荷和剪切负荷被认为在足部溃疡的发展中发挥着重要作用，并且可能是改善 DFU 评估的有价值的指标。然而，尽管有其前景，但足底载荷测量目前的临床应用有限，主要是由于缺乏可靠的测量技术，特别是剪切载荷测量。在本文中，我们报告了一种新型三轴力传感器的设计和评估，该传感器可同时测量脚底表面的法向载荷和剪切载荷。该传感器由一组感应传感线圈组成，其上方的超弹性弹性体上放置有导电目标。负载下目标的移动会影响线圈电感，线圈电感由嵌入式系统测量和数字化。使用计算有限元模型，我们研究了传感线圈的形式和配置对传感器性能的影响。配置有四方形线圈和最大匝数的传感器为足底负载测量提供了最佳性能。使用神经网络制造和校准原型，以映射传感器输出和所施加的三轴负载之间的非线性关系。实验评估表明，该三轴传感器能够有效检测±16 N的剪切载荷和高达105 N的正常载荷（均方根误差分别为1.05 N和1.73 N），具有高性能。总体而言，该传感器为足底正常载荷和剪切载荷测量提供了有前景的基础，这对于改进 DFU 评估至关重要。
Diabetic foot ulcers (DFUs) are a severe global public health issue. Plantar normal and shear load are believed to play an important role in the development of foot ulcers and could be a valuable indicator to improve assessment of DFUs. However, despite their promise, plantar load measurements currently have limited clinical application, primarily due to the lack of reliable measurement techniques particularly for shear load measurements. In this paper we report on the design and evaluation of a novel tri-axis force sensor to measure both normal and shear load on the foot’s plantar surface simultaneously. The sensor consists of a group of inductive sensing coils above which a conductive target is placed on a hyperelastic elastomer. Movement of the target under load affects the coil inductances which are measured and digitized by an embedded system. Using a computational finite element model, we investigated the influence of sensing coil form and configuration on sensor performance. A sensor configured with four-square coils and maximal turns provided the best performance for plantar load measurements. A prototype was fabricated and calibrated using a neural network to map the non-linear relationship between the sensor output and the applied tri-axis load. Experimental evaluation indicates that the tri-axis sensor can effectively detect shear load of ±16 N and normal load up to 105 N (RMS errors: 1.05 N and 1.73 N respectively) with a high performance. Overall, this sensor provides a promising basis for plantar normal and shear load measurement which are crucial for improved assessment of DFU.