Proportional Myoelectric Control of a Virtual Inverted Pendulum Using Residual Antagonistic Muscles: Toward Voluntary Postural Control
Proportional Myoelectric Control of a Virtual Inverted Pendulum Using Residual Antagonistic Muscles: Toward Voluntary Postural Control
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DOI：
10.1109/tnsre.2019.2922102
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发表时间：
2019-07-01
影响因子：
4.9
通讯作者：
Huang, He
中科院分区：
文献类型：
--
作者：
Fleming, Aaron;Huang, Stephanie;Huang, He
本文旨在研究经胫骨截肢者是否能够协调下行神经指令以对抗残留的踝部肌肉，以执行需要连续、精确控制的动态任务。为了实现这一目标，我们开发了一种虚拟倒立摆，它本质上是不稳定的，并在站立姿势下模仿人类的动力学。平衡这一动力系统需要连续的输入，与分别从(残留的)胫骨前肌(TA)和外侧腓肠肌(GAS)记录的肌电(EMG)大小成比例。招募了6名肢体健全的截肢者和6名经胫骨截肢的人，要求他们在10次90-S试验中平衡倒立摆。结果表明，截肢者能够通过比例肌电控制来控制这个不稳定的动力学系统，但他们的表现逊于身体健全的受试者，后者将钟摆保持在更靠近中心的位置(p=0.041)。与最初两个试验中的表现相比，截肢者在最后两个试验中显著减少了摆落次数(p=0.0329)和摆动大小(p=0.048)，从而提高了表现。然而，截肢者的改善程度因受试者而异。截肢者展示了不同的任务适应策略，包括减少错误的残余肌肉收缩，为任务发展适当的状态-动作关系(钟摆状态-肌电激活)，和/或随着任务执行效率的提高(即增加静止和摆动最小化)减少肌肉控制变异性。结果提示，在对截肢者进行动力系统中协调对抗残馀肌肉的训练后，对动力型踝关节假体实施比例肌电控制，以辅助预期和补偿性姿势调整等姿势控制机制可能是可行的。
This paper aims to investigate whether transtibial amputees are capable of coordinating the descending neural commands to antagonistic residual ankle muscles for performing dynamic tasks that require continuous, precise control. To achieve this goal, we developed a virtual inverted pendulum that was inherently unstable and mimicked human-like dynamics in a standing posture. Balancing this dynamic system requires continuous inputs, proportional to electromyography (EMG) magnitudes recorded from (residual) tibialis anterior (TA) and lateral gastrocnemius muscles (GAS), respectively. The six able-bodied and six transtibial amputees were recruited and asked to balance the inverted pendulum for ten 90-s trials. The results showed that the amputees were capable of controlling this unstable dynamic system with a proportional myoelectric control; however, they underperformed the able-bodied subjects, who maintained the pendulum closer to center (p = 0.041). Compared to the performance in the initial two trials, amputees improved the performance by significantly reducing the number of pendulum falls (p = 0.0329) and sway size (p = 0.048) in the final two trials. However, the amount of improvement varied across amputee subjects. Amputee subjects demonstrated different task adaptation strategies, including reduction of erroneous residual muscle contractions, development of an appropriate state-action (pendulum state-EMG activation) relationship for the task, and/or reduction of muscle control variability with the improved task performance efficiency (i.e., increased inactivity and sway minimization). The results suggest that after the training of transtibial amputees in coordinating antagonistic residual muscles in dynamic systems, it may be feasible to implement the proportional myoelectric control of the powered ankle prostheses in order to assist the postural control mechanisms, such as anticipatory and compensatory postural adjustments.