Self-selected walking speed is an important aspect of mobility. Exoskeletons can increase walking speed, but the mechanisms behind these changes and the upper limits on performance are unknown. Human-in-the-loop optimization is a technique for identifying exoskeleton characteristics that maximize the benefits of assistance, which has been critical to achieving large improvements in energy economy. In this study, we used human-in-the-loop optimization to test whether large improvements in self-selected walking speed are possible through ankle exoskeleton assistance. Healthy participants (N =10) were instructed to walk at a comfortable speed on a self-paced treadmill while wearing tethered ankle exoskeletons. An algorithm sequentially applied different patterns of exoskeleton torque and estimated the speed-optimal pattern, which was then evaluated in separate trials. With torque optimized for speed, participants walked 42% faster than in normal shoes (1.83 ms ⁻¹ vs. 1.31 ms ⁻¹ ; Tukey HSD, $p = 4 \times 10^{-8}$ ), with speed increases ranging from 6% to 91%. Participants walked faster with speed-optimized torque than with torque optimized for energy consumption (1.55 ms ⁻¹ ) or torque chosen to induce slow walking (1.18 ms ⁻¹ ). Gait characteristics with speed-optimized torque were highly variable across participants, and changes in metabolic cost of transport ranged from a 31% decrease to a 78% increase, with a decrease of 2% on average. These results demonstrate that ankle exoskeletons can facilitate large increases in self-selected walking speed, which could benefit older adults and others with reduced walking speed.

中文翻译：

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优化外骨骼辅助，以实现更快的自选行走

自行选择的步行速度是移动性的重要方面。外骨骼可以提高步行速度，但这些变化背后的机制和性能上限尚不明确。循环中的人为优化是一种用于识别外骨骼特征的技术，该特征可以最大程度地提高援助的效益，这对实现能源经济的大幅改善至关重要。在这项研究中，我们使用人在循环中的优化方法来测试通过脚踝外骨骼的辅助是否有可能大幅改善自我选择的步行速度。健康的参与者（N = 10）被指示以脚步系绳踝外骨骼在自定速度的跑步机上以舒适的速度行走。一种算法依次应用了不同的外骨骼扭矩模式，并估算了速度最佳模式，然后在单独的试验中进行评估。通过针对速度进行了优化的扭矩，参与者的行走速度比普通鞋子快了42％（1.83毫秒） ^-1和1.31 ms ^-1 ; Tukey HSD， $ p = 4 \ times 10 ^ {-8} $ ），速度从6％增至91％。与速度优化的扭矩相比，参与者的行走速度更快，而能量消耗优化的扭矩（1.55 ms ^-1 ）或为引起慢速行走而选择的扭矩（1.18 ms ^-1 ）更快 。速度最佳扭矩的步态特征在参与者之间变化很大，运输代谢成本的变化从降低31％到提高78％不等，平均降低2％。这些结果表明，踝关节外骨骼可以促进自我选择的步行速度的大幅提高，这可以使老年人和步行速度降低的其他人受益。