Background

The effects of lower limb (L/L) control options, developed for overground walking with a wearable robotic exoskeleton (WRE), on the neuromotor control of L/L muscles [i.e., muscle synergies (MSs)] during walking remain uncertain.

Objective

To gain initial insights regarding the effects of different control options on the number of MSs at the L/L and on their muscle weighting within each MS when walking with a WRE.

Methods

Twenty able-bodied adults walked overground without and with the WRE set at two control options with a predetermined foot pathway imposed by the WRE, and at three other control options with free L/L kinematics in the sagittal plane. Surface electromyography of eight right L/L muscles was recorded. MSs were extracted using a non-negative matrix factorisation algorithm. Cosine similarity and correlation coefficients characterised similarities between the MSs characteristics.

Results

Freely moving the L/L in the sagittal plane (i.e., non-trajectory controlled options) during WRE walking best duplicated typical MSs extracted when walking without WRE. Conversely, WRE walking while fully controlling the L/L trajectory presented the lowest correlations to all MSs extracted when walking without WRE, especially during early swing and L/L deceleration.

Conclusion

Neuromotor control of L/L muscles is affected by the selected control option during WRE walking, particularly when a predetermined foot pathway is imposed.

Significance

This exploratory study represents the first step in informing the decision-making process regarding the use of different L/L control options when using WRE and calls for further research among adults with sensorimotor impairments.

中文翻译：

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机器人外骨骼控制选项对地上行走过程中下肢肌肉协同作用的影响：一项针对健全成年人的探索性研究。

背景

为使用可穿戴机器人外骨骼 (WRE) 进行地上行走而开发的下肢 (L/L) 控制选项对行走期间 L/L 肌肉的神经运动控制 [即肌肉协同作用 (MSs)] 的影响仍不确定。

客观的

初步了解不同控制选项对 L/L 处 MS 数量的影响，以及使用 WRE 行走时每个 MS 内的肌肉权重。

方法

二十名身体健全的成年人在没有和有 WRE 的情况下在地上行走，WRE 设置为两个控制选项，其中包含 WRE 施加的预定步行路径，以及其他三个控制选项，在矢状面上具有自由 L/L 运动学。记录了八块右侧 L/L 肌肉的表面肌电图。使用非负矩阵分解算法提取 MS。余弦相似性和相关系数表征了 MS 特征之间的相似性。

结果

在 WRE 行走期间在矢状面自由移动 L/L（即，非轨迹控制选项）最好复制在没有 WRE 的情况下行走时提取的典型 MS。相反，在完全控制 L/L 轨迹的情况下，WRE 行走与在没有 WRE 的情况下行走时提取的所有 MS 的相关性最低，尤其是在早期摆动和 L/L 减速期间。

结论

在 WRE 步行期间，L/L 肌肉的神经运动控制受所选控制选项的影响，尤其是在施加预定的足部路径时。

意义

这项探索性研究代表了在使用 WRE 时为有关使用不同 L/L 控制选项的决策过程提供信息的第一步，并呼吁对有感觉运动障碍的成年人进行进一步研究。