The study of human balance recovery strategies is important for human balance rehabilitation and humanoid robot balance control. To date, many efforts have been made to improve balance during quiet standing and walking motions. Arm usage (arm strategy) has been proposed to control the balance during walking motion in the literature. However, limited research exists on the contributions of the arm strategy for balance recovery during quiet standing along with ankle and hip strategy. Therefore, in this study, we built a simplified model with arms and proposed a controller based on nonlinear model predictive control to achieve human-like balance control. Three arm states of the model, namely, active arms, passive arms, and fixed arms, were considered to discuss the contributions of arm usage to human balance recovery during quiet standing. Furthermore, various indexes such as root mean square deviation of joint angles and recovery energy consumption were verified to reveal the mechanism behind arm strategy employment. In this study, we demonstrate to computationally reproduce human-like balance recovery with and without arm rotation during quiet standing while applying different magnitudes of perturbing forces on the upper body. In addition, the conducted human balance experiments are presented as supplementary information in this paper to demonstrate the concept on a typical example of arm strategy.

中文翻译：

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通过模型预测控制复制人类手臂策略及其对平衡恢复的贡献

人体平衡恢复策略的研究对于人体平衡康复和类人机器人平衡控制具有重要意义。迄今为止，已经做出许多努力来改善安静的站立和行走动作期间的平衡。在文献中已经提出了手臂使用（手臂策略）来控制步行运动中的平衡。但是，关于手臂策略在安静站立期间以及踝关节和髋关节策略对平衡恢复的贡献方面的研究还很有限。因此，在本研究中，我们建立了带手臂的简化模型，并提出了一种基于非线性模型预测控制的控制器，以实现类似于人的平衡控制。考虑了模型的三个手臂状态，即主动手臂，被动手臂和固定手臂，以讨论静静站立时手臂使用对人体平衡恢复的贡献。此外，还验证了关节角度的均方根偏差和恢复能量消耗等各种指标，以揭示采用手臂策略的背后机制。在这项研究中，我们证明了在安静站立时，在上半身上施加不同大小的扰动力时，无论有无手臂旋转，都可以通过计算重现类似人的平衡恢复。此外，本文还进行了人体平衡实验，作为补充信息，以典型的手臂策略示例来演示这一概念。我们证明了在安静站立时，在上半身上施加不同大小的扰动力时，无论有无手臂旋转，都可以通过计算来再现类似于人的平衡恢复。此外，本文还进行了人体平衡实验，作为补充信息，以典型的手臂策略示例来演示这一概念。我们证明了在安静站立时，在上半身上施加不同大小的扰动力时，无论有无手臂旋转，都可以通过计算来再现类似于人的平衡恢复。此外，本文还进行了人体平衡实验，作为补充信息，以典型的手臂策略示例来演示这一概念。