Department of Industrial and Systems Engineering, Virginia Tech, Blacksburg, VA 24061, USA.
Department of Industrial Engineering, Clemson University, Clemson, SC 29634, USA.
Gait Posture. 2022 Feb;92:181-190. doi: 10.1016/j.gaitpost.2021.11.028. Epub 2021 Nov 25.
Back-support exoskeletons (BSEs) are a promising intervention to mitigate physical demands at work. Although growing evidence indicates that BSEs can reduce low-back physical demands, there is limited understanding of potential unintended consequences of BSE use, including the risk of falls.
Does using a BSE adversely affect gait performance and stability, and are such effects dependent on specific BSE external torque characteristics?
Twenty participants (10 M, 10 F) completed five level over-ground walking trials and a five-minute treadmill walking trial while wearing a BSE (backX™) with three different levels of external torque (i.e., no torque, low torque, and high torque) and in a control (no-exoskeleton) condition. Spatiotemporal gait patterns, stride-to-stride gait variability measures, required coefficient-of-friction (RCoF), and minimum foot clearance (MFC) were determined, to assess gait performance. Gait stability was quantified using the maximum Lyapunov exponent (MLE) of trunk kinematics and the margin-of-stability (MoS).
Using the backX™ with high supportive torque decreased slip risk (7% decrease in RCoF) and slightly improved trunk stability (3% decrease in MLE). However, it also decreased step length (1%), increased step width (10%) and increased gait variability (8-19%). Changes in MoS were complex: while MoS at heel strike decreased in the AP direction, it increased in the ML direction. There was a rather large decrease in MoS (26%) in the ML direction during the swing phase.
This is the first study to quantify the effects of wearing a passive BSE with multiple supportive torque levels on gait performance and stability during level walking. Our results, showing that the external torque of the BSE may adversely affect gait step width, variability, and dynamic stability, can contribute to better design and practice guidelines to facilitate the safe adoption of BSEs in the workplace.
背部支撑式外骨骼（BSE）是一种减轻工作中体力需求的有前途的干预措施。尽管越来越多的证据表明 BSE 可以降低背部的体力需求，但对于 BSE 使用的潜在意外后果，包括跌倒风险，人们的理解有限。
使用 BSE 是否会对步态性能和稳定性产生不利影响，而这些影响是否取决于 BSE 外部扭矩特性？
20 名参与者（10 名男性，10 名女性）在穿着 BSE（backX™）并施加三种不同水平的外部扭矩（即无扭矩、低扭矩和高扭矩）和控制（无外骨骼）条件下完成了五次平地行走试验和五分钟跑步机行走试验。评估步态性能的指标包括时空步态模式、步长间步态变异性测量、所需摩擦系数（RCoF）和最小足间隙（MFC）。使用躯干运动学的最大 Lyapunov 指数（MLE）和稳定裕度（MoS）来量化步态稳定性。
使用具有高支撑扭矩的 backX™ 降低了滑倒风险（RCoF 降低了 7%）并略微改善了躯干稳定性（MLE 降低了 3%）。然而，它也降低了步长（1%）、增加了步宽（10%）并增加了步态变异性（8-19%）。MoS 的变化很复杂：在脚跟触地时，MoS 在 AP 方向上减小，而在 ML 方向上增大。在摆动阶段，MoS 在 ML 方向上减小了 26%。
这是第一项研究，定量分析了穿着具有多种支撑扭矩水平的被动 BSE 对平地行走时步态性能和稳定性的影响。我们的结果表明，BSE 的外部扭矩可能会对步态步宽、变异性和动态稳定性产生不利影响，这有助于更好地设计和实践指南，以促进 BSE 在工作场所的安全采用。
