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%.

中文翻译：

---

支持关节平衡的双关节被动式防风衣可以减少步行的代谢成本。

如今，仅针对行动不便的人开发辅助设备的重点已经转向增强健全人的身体能力。结果，对廉价和柔软的可穿戴外骨骼（称为外衣）设计的兴趣明显增加。本文介绍了一种带有两个双关节可变刚度元件的被动式下肢外衣。这些元素与腿部的绳肌平行，并基于新版本的FMCH（力调制顺应性臀部）控制框架进行控制，其中力反馈被长度反馈（称为LMCH）代替。运用腿长反馈的主要见解是开发被动式防寒服。幸运的是，类似于FMCH，LMCH方法还可以预测类似人的平衡控制行为，例如在人的行走中观察到的VPP（虚拟枢轴点）现象。我们使用人类步行的神经肌肉模型进行的仿真结果表明，该方法可以将人类步行的代谢成本降低10％。此外，为了验证设计和仿真结果，构建了这种外装服的初步版本，该外装服由具有恒定刚度的弹簧组成。对八名健康受试者进行了实验。我们比较了穿着防磨服但弹簧松弛的行走实验与使用适当弹簧的行走实验之间的比较。它显示被动双关节弹性可导致代谢减少14.7 [公式：参见文本] 4.27％。更重要的是，与无辅助行走相比（不穿防护服时），