Maintaining balance throughout daily activities is challenging because of the unstable nature of the human body. For instance, a person’s delayed reaction times limit their ability to restore balance after disturbances. Wearable exoskeletons have the potential to enhance user balance after a disturbance by reacting faster than physiologically possible. However, “artificially fast” balance-correcting exoskeleton torque may interfere with the user’s ensuing physiological responses, consequently hindering the overall reactive balance response. Here, we show that exoskeletons need to react faster than physiological responses to improve standing balance after postural perturbations. Delivering ankle exoskeleton torque before the onset of physiological reactive joint moments improved standing balance by 9%, whereas delaying torque onset to coincide with that of physiological reactive ankle moments did not. In addition, artificially fast exoskeleton torque disrupted the ankle mechanics that generate initial local sensory feedback, but the initial reactive soleus muscle activity was only reduced by 18% versus baseline. More variance of the initial reactive soleus muscle activity was accounted for using delayed and scaled whole-body mechanics [specifically center of mass (CoM) velocity] versus local ankle—or soleus fascicle—mechanics, supporting the notion that reactive muscle activity is commanded to achieve task-level goals, such as maintaining balance. Together, to elicit symbiotic human-exoskeleton balance control, device torque may need to be informed by mechanical estimates of global sensory feedback, such as CoM kinematics, that precede physiological responses.

中文翻译：

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外骨骼需要比生理反应更快的反应才能改善站立平衡

由于人体的不稳定特性，在日常活动中保持平衡具有挑战性。例如，一个人的延迟反应时间限制了他们在受到干扰后恢复平衡的能力。可穿戴外骨骼有可能通过比生理上可能更快的反应来增强用户在受到干扰后的平衡。然而，“人工快速”平衡校正外骨骼扭矩可能会干扰用户随后的生理反应，从而阻碍整体反应性平衡反应。在这里，我们表明外骨骼需要比生理反应更快的反应才能改善姿势扰动后的站立平衡。在生理反应性关节力矩出现之前提供踝关节外骨骼扭矩可将站立平衡提高 9%，而延迟扭矩开始以与生理反应性脚踝力矩一致则没有。此外，人为的快速外骨骼扭矩扰乱了产生初始局部感觉反馈的踝关节力学，但初始反应性比目鱼肌活动与基线相比仅减少了 18%。使用延迟和缩放的全身力学 [特别是质心 (CoM) 速度] 与局部踝关节或比目鱼肌分束力学相比，初始反应性比目鱼肌活动的更多差异被解释为，支持反应性肌肉活动被命令的概念实现任务级目标，例如保持平衡。总之，为了引发共生的人体外骨骼平衡控制，设备扭矩可能需要通过全局感官反馈的机械估计来告知，例如 CoM 运动学，