OBJECTIVE To investigate postural control related to a lower limb exoskeleton (Chairless Chair) when (a) reaching for a working tool, and (b) an external perturbation occurs. BACKGROUND Lower limb exoskeletons aiming to reduce physical load associated with prolonged standing may impair workers' postural control and increase the risk of falling. METHOD Forty-five males were reaching for an object (3-kg dumbbell) at the lateral end of their reaching area without the exoskeleton in upright standing (STAND) and with the exoskeleton at a high (EXOHIGH.SEAT) and low sitting position (EXOLOW.SEAT). The task was performed with the object placed in three different angles (120°, 150°, and 180°) in the transversal plane. The minimum absolute static postural stability (SSABS.MIN) as the shortest distance (mm) of the center of pressure to the base of support border was measured (zero indicates risk of falling). Additionally, eight subjects were standing without the exoskeleton or sitting on it (EXOHIGH.SEAT and EXOLOW.SEAT) while being pulled backward. The tilting moment when subjects lost their balance was assessed. RESULTS SSABS.MIN was lower when using the exoskeleton (p < .05) but still about 17 mm. The location of the object to be reached had no influence. Tilting moments of less than 30 nm were sufficient to let people fall backward when sitting on the exoskeleton (50 nm for STAND). CONCLUSION Impairments in postural control by the exoskeleton may not be relevant when reaching laterally for objects up to 3 kg. When an external perturbation occurs, the risk of falling may be much higher; irrespective of factors like uneven or slippery flooring. APPLICATION The risk of falling using the exoskeleton seems to be low when reaching laterally for an object of up to 3 kg. In situations where, for example, a collision with coworkers is likely, this exoskeleton is not recommended.

中文翻译：

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使用工业下肢外骨骼时的姿势控制：接触工作工具和外部扰动的影响

目的 研究当 (a) 伸手去拿工作工具和 (b) 发生外部扰动时与下肢外骨骼（无椅椅）相关的姿势控制。背景技术旨在减少与长时间站立相关的身体负荷的下肢外骨骼可能会损害工人的姿势控制并增加跌倒的风险。方法 45 名男性在直立（STAND）和外骨骼处于高位（EXOHIGH.SEAT）和低坐位（ EXOLOW.SEAT）。该任务是在对象以三个不同的角度（120°、150° 和 180°）放置在横向平面中的情况下执行的。最小绝对静态姿势稳定性 (SSABS. MIN）作为压力中心到支撑边界底部的最短距离（mm）被测量（零表示有跌倒的风险）。此外，八名受试者在没有外骨骼的情况下站立或坐在其上（EXOHIGH.SEAT 和 EXOLOW.SEAT），同时被向后拉。评估受试者失去平衡时的倾斜时刻。结果 使用外骨骼时 SSABS.MIN 较低 (p < .05)，但仍约为 17 mm。要到达的对象的位置没有影响。当人们坐在外骨骼上时，小于 30 nm 的倾斜力矩足以让人们向后跌倒（STAND 为 50 nm）。结论 外骨骼对姿势控制的损害可能与横向接触重达 3 kg 的物体无关。当外部扰动发生时，跌倒的风险可能会高得多；不考虑地板不平整或湿滑等因素。应用 当横向伸手去拿重达 3 kg 的物体时，使用外骨骼跌倒的风险似乎很低。例如，在可能与同事发生碰撞的情况下，不建议使用这种外骨骼。