Beckett Thermal Solutions S.r.l, Formigine (MO), Italy.
Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Rome, Italy.
J Neuroeng Rehabil. 2020 Jul 27;17(1):104. doi: 10.1186/s12984-020-00719-w.
Previous studies have shown that passive-elastic exoskeletons with springs in parallel with the ankle can reduce the metabolic cost of walking. We developed and tested the use of an unpowered passive-elastic exoskeleton for walking that stores elastic energy in a spring from knee extension at the end of the leg swing phase, and then releases this energy to assist ankle plantarflexion at the end of the stance phase prior to toe-off. The exoskeleton uses a system of ratchets and pawls to store and return elastic energy through compression and release of metal springs that act in parallel with the knee and ankle, respectively. We hypothesized that, due to the assistance provided by the exoskeleton, net metabolic power would be reduced compared to walking without using an exoskeleton.
We compared the net metabolic power required to walk when the exoskeleton only acts at the knee to resist extension at the end of the leg swing phase, to that required to walk when the stored elastic energy from knee extension is released to assist ankle plantarflexion at the end of the stance phase prior to toe-off. Eight (4 M, 4F) subjects walked at 1.25 m/s on a force-measuring treadmill with and without using the exoskeleton while we measured their metabolic rates, ground reaction forces, and center of pressure.
We found that when subjects used the exoskeleton with energy stored from knee extension and released for ankle plantarflexion, average net metabolic power was 11% lower than when subjects walked while wearing the exoskeleton with the springs disengaged (p = 0.007), but was 23% higher compared to walking without the exoskeleton (p < 0.0001).
The use of a novel passive-elastic exoskeleton that stores and returns energy in parallel with the knee and ankle, respectively, has the potential to improve the metabolic cost of walking. Future studies are needed to optimize the design and elucidate the underlying biomechanical and physiological effects of using an exoskeleton that acts in parallel with the knee and ankle. Moreover, addressing and improving the exoskeletal design by reducing and closely aligning the mass of the exoskeleton could further improve the metabolic cost of walking.
先前的研究表明，带有与脚踝平行的弹簧的被动弹性外骨骼可以降低步行的代谢成本。我们开发并测试了一种无动力被动弹性外骨骼的使用，该外骨骼通过在腿部摆动阶段结束时从膝关节伸展存储弹性能量，然后在站立阶段结束前释放此能量来辅助踝关节跖屈，从而在脚趾离地前。外骨骼使用棘轮和棘爪系统，通过压缩和释放分别与膝盖和脚踝平行作用的金属弹簧来存储和返回弹性能量。我们假设，由于外骨骼提供的辅助，与不使用外骨骼相比，净代谢功率将会降低。
我们比较了外骨骼仅在腿部摆动阶段结束时作用于膝盖以抵抗伸展所需的净代谢功率，与从膝关节伸展存储的弹性能量释放以辅助站立阶段结束前的踝关节跖屈所需的净代谢功率。八名（4 名男性，4 名女性）受试者在测力跑步机上以 1.25 m/s 的速度行走，同时使用和不使用外骨骼，同时测量他们的代谢率、地面反作用力和中心压力。
我们发现，当受试者使用从膝关节伸展存储并释放用于踝关节跖屈的能量的外骨骼时，平均净代谢功率比当受试者穿着外骨骼且弹簧脱离时行走时低 11%（p=0.007），但比不使用外骨骼行走时高 23%（p<0.0001）。
使用一种新型的被动弹性外骨骼，分别在膝关节和踝关节处存储和返回能量，具有降低步行代谢成本的潜力。需要进一步研究来优化设计，并阐明使用与膝关节和踝关节平行作用的外骨骼的潜在生物力学和生理影响。此外，通过减小并紧密对齐外骨骼的质量来改进外骨骼设计，也可以进一步降低步行的代谢成本。
