Institute of Rehabilitation and Medical Robotics, State Key Lab of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China.
Institute of Robotics and Automation Information System and the Tianjin Key Laboratory of Intelligent Robotics, Nankai University, Tianjin, 300071, China.
J Neuroeng Rehabil. 2021 Jun 6;18(1):95. doi: 10.1186/s12984-021-00893-5.
Walking and running are the most common means of locomotion in human daily life. People have made advances in developing separate exoskeletons to reduce the metabolic rate of walking or running. However, the combined requirements of overcoming the fundamental biomechanical differences between the two gaits and minimizing the metabolic penalty of the exoskeleton mass make it challenging to develop an exoskeleton that can reduce the metabolic energy during both gaits. Here we show that the metabolic energy of both walking and running can be reduced by regulating the metabolic energy of hip flexion during the common energy consumption period of the two gaits using an unpowered hip exoskeleton.
We analyzed the metabolic rates, muscle activities and spatiotemporal parameters of 9 healthy subjects (mean ± s.t.d; 24.9 ± 3.7 years, 66.9 ± 8.7 kg, 1.76 ± 0.05 m) walking on a treadmill at a speed of 1.5 m s and running at a speed of 2.5 m s with different spring stiffnesses. After obtaining the optimal spring stiffness, we recruited the participants to walk and run with the assistance from a spring with optimal stiffness at different speeds to demonstrate the generality of the proposed approach.
We found that the common optimal exoskeleton spring stiffness for walking and running was 83 Nm Rad, corresponding to 7.2% ± 1.2% (mean ± s.e.m, paired t-test p < 0.01) and 6.8% ± 1.0% (p < 0.01) metabolic reductions compared to walking and running without exoskeleton. The metabolic energy within the tested speed range can be reduced with the assistance except for low-speed walking (1.0 m s). Participants showed different changes in muscle activities with the assistance of the proposed exoskeleton.
This paper first demonstrates that the metabolic cost of walking and running can be reduced using an unpowered hip exoskeleton to regulate the metabolic energy of hip flexion. The design method based on analyzing the common energy consumption characteristics between gaits may inspire future exoskeletons that assist multiple gaits. The results of different changes in muscle activities provide new insight into human response to the same assistive principle for different gaits (walking and running).
行走和跑步是人类日常生活中最常见的运动方式。人们已经在开发单独的外骨骼方面取得了进展，以降低行走或跑步的代谢率。然而，要开发一种既能在两种步态下都能降低代谢能量，又能最小化外骨骼质量代谢惩罚的外骨骼，就需要克服这两种步态之间基本生物力学差异的综合要求，这极具挑战性。在这里，我们展示了使用无动力髋关节外骨骼，在两种步态的共同能耗期内调节髋关节屈曲的代谢能量，可以降低行走和跑步的代谢能量。
我们分析了 9 名健康受试者（平均±标准差；24.9±3.7 岁，66.9±8.7 公斤，1.76±0.05 米）在跑步机上以 1.5 m s 的速度行走和以 2.5 m s 的速度跑步时的代谢率、肌肉活动和时空参数，使用不同的弹簧刚度。在获得最佳弹簧刚度后，我们招募参与者以不同速度在最佳刚度弹簧的辅助下行走和跑步，以证明所提出方法的通用性。
我们发现，行走和跑步的共同最佳外骨骼弹簧刚度为 83 Nm Rad，与无外骨骼行走和跑步相比，分别降低了 7.2%±1.2%（平均值±标准误差，配对 t 检验 p<0.01）和 6.8%±1.0%（p<0.01）。在测试速度范围内，除了低速行走（1.0 m s）外，代谢能量都可以通过辅助降低。参与者在使用所提出的外骨骼时，肌肉活动的变化不同。
本文首次证明，使用无动力髋关节外骨骼调节髋关节屈曲的代谢能量，可以降低行走和跑步的代谢成本。这种基于分析步态共同能耗特征的设计方法可能会启发未来辅助多种步态的外骨骼。不同肌肉活动变化的结果为人类对不同步态（行走和跑步）相同辅助原理的反应提供了新的见解。
