School of ECE, College of Engineering, University of Tehran, Tehran, Iran.
Bioinspir Biomim. 2020 Mar 20;15(3):036009. doi: 10.1088/1748-3190/ab70ed.
Nowadays, the focus on the development of assistive devices just for people with mobility disorders has shifted towards enhancing physical abilities of able-bodied humans. As a result, the interest in the design of cheap and soft wearable exoskeletons (called exosuits) is distinctly growing. In this paper, a passive lower limb exosuit with two biarticular variable stiffness elements is introduced. These elements are in parallel to the hamstring muscles of the leg and controlled based on a new version of the FMCH (force modulated compliant hip) control framework in which the force feedback is replaced by the length feedback (called LMCH). The main insight to employ leg length feedback is to develop a passive exosuit. Fortunately, similar to FMCH, the LMCH method also predicts human-like balance control behaviours, such as the VPP (virtual pivot point) phenomenon, observed in human walking. Our simulation results, using a neuromuscular model of human walking, demonstrate that this method could reduce the metabolic cost of human walking by 10%. Furthermore, to validate the design and simulation results, a preliminary version of this exosuit comprised of springs with constant stiffness was built. An experiment with eight healthy subjects was performed. We made a comparison between the walking experiments while the exosuit is worn but the springs were slack and those when the appropriate springs were contributing. It shows that passive biarticular elasticity can result in a metabolic reduction of 14.7 [Formula: see text] 4.27%. More importantly, compared to unassisted walking (when exosuit is not worn), such a passive device can reduce walking metabolic cost by 4.68 [Formula: see text] 4.24%.
如今，针对行动障碍人士的辅助设备研发重点已逐渐转向提升健全人士的身体机能。因此，人们对廉价且柔软的可穿戴外骨骼（即外骨骼套装）设计的兴趣显著增加。本文介绍了一种带有两个双关节可变刚度元件的被动下肢外骨骼。这些元件与腿部的腘绳肌平行，并根据 FMCH（力调制顺应性髋关节）控制框架的新版本进行控制，其中力反馈被长度反馈（称为 LMCH）取代。使用腿部长度反馈的主要目的是开发一种被动外骨骼。幸运的是，与 FMCH 类似，LMCH 方法也预测了类似于人类的平衡控制行为，例如在人类行走中观察到的 VPP（虚拟枢轴点）现象。我们使用人类行走的神经肌肉模型的仿真结果表明，这种方法可以将人类行走的代谢成本降低 10%。此外，为了验证设计和仿真结果，我们构建了一个由具有恒定刚度的弹簧组成的该外骨骼的初步版本。进行了一项包含 8 位健康受试者的实验。我们比较了外骨骼佩戴但弹簧松弛时和适当的弹簧起作用时的行走实验。结果表明，双关节弹性可以使代谢降低 14.7 [Formula: see text] 4.27%。更重要的是，与非辅助行走（即不佩戴外骨骼时）相比，这种被动装置可以将行走代谢成本降低 4.68 [Formula: see text] 4.24%。
