A Phase-Shifting Based Human Gait Phase Estimation for Powered Transfemoral Prostheses
A Phase-Shifting Based Human Gait Phase Estimation for Powered Transfemoral Prostheses
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DOI：
10.1109/lra.2021.3068907
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发表时间：
2021-07-01
影响因子：
5.2
通讯作者：
Hur, Pilwon
中科院分区：
文献类型：
--
作者：
Hong, Woolim;Kumar, Namita Anil;Hur, Pilwon
相位变量是连续的实值函数，其参数化步态周期。因此，它们可以用于估计动力假肢用户的行走状态。通常将相位变量表示为大腿角度的函数。该方法假设大腿角度轮廓及其积分为正弦曲线。然而，该假设在较低的步行速度下不成立，这导致不准确的脚跟撞击检测。在这项研究中，我们表明，大腿的角度和它的积分从理想的正弦波相移通过分析健全和截肢受试者行走数据。然后，我们提出了一种新的相位变量，结合相移，即使在较低的步行速度是准确的。我们在仿真器研究中测试了经股骨假体上提出的相移相位变量的两个变体。结果表明，相移提高了脚跟撞击检测。此外，相移改善了步态周期内相位变量的线性度。对膝关节和踝关节相位图的分析表明，相移导致与极限环的偏差较小。
Phase variables are continuous real-valued functions which parameterize the gait cycle. As such, they can be used to estimate a powered prosthesis user's walking state. It is common to represent the phase variable as a function of the thigh angle. This approach assumes the thigh angle profile and its integral to be sinusoids. However, this assumption does not hold at lower walking speeds which leads to inaccurate heel-strike detection. In this study, we show that the thigh angle and its integral are phase-shifted from the ideal sinusoids by analyzing both able-bodied and amputee subject walking data. We then propose a novel phase variable incorporating phase-shift that is accurate even at lower walking speeds. We tested two variants of the proposed phase-shifted phase variable on a transfemoral prosthesis in an emulator study. Results show that phase-shifting improves heel-strike detection. Additionally, phase-shifting improves the linearity of the phase variable over the gait cycle. Analysis of the knee and ankle phase portraits showed that phase-shifting results in less deviations from the limit cycle.