Powered ankle-foot prosthesis to assist level-ground and stair-descent gaits
Powered ankle-foot prosthesis to assist level-ground and stair-descent gaits
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DOI：
10.1016/j.neunet.2008.03.006
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发表时间：
2008-05-01
期刊：
影响因子：
7.8
通讯作者：
Herr, Hugh
中科院分区：
文献类型：
--
作者：
Au, Samuel;Berniker, Max;Herr, Hugh
人的脚踝在站立行走期间改变阻抗并提供净正功。相比之下，市售的踝足假体在站立时是被动的，这给经胫截肢者带来了许多临床问题，包括不对称的步态模式、更高的步态代谢和较差的减震。在这项研究中，我们开发并评估了一种肌电驱动的有限状态控制器，用于动力踝足假体，该控制器可以调节站立时的阻抗和功率输出。该系统采用外部假体局部测量的感觉输入和残肢肌肉测量的肌电输入。利用局部假肢传感，我们首先开发了两个有限状态控制器来产生水平地面和楼梯下降步态的仿生运动模式。然后，我们使用肌电信号作为控制命令来管理这些有限状态控制器之间的转换。为了从平地过渡到楼梯，截肢者弯曲腓肠肌，在末端摆动时触发假肢踝关节到足底弯曲，并启动楼梯下降状态机算法。为了回到平地行走，截肢者弯曲胫骨前肌，触发踝关节在末端摆动时保持背屈，并启动平地状态机算法。作为临床疗效的初步评估，我们在一个跨胫截肢者身上测试了该装置，同时使用了所提出的控制器和传统的被动弹性控制。我们发现截肢者可以通过直接的肌肉激活在有限状态控制器之间稳健地转换，允许从平地快速过渡到楼梯行走模式。此外，我们发现所提出的有限状态控制器导致更仿生的踝关节反应，在平地行走时产生净推进功，在楼梯下降时产生更大的减震。这项研究的结果强调了假腿控制器利用神经信号来触发适合地形的局部假腿行为的潜力。(C) 2008 Elsevier Ltd版权所有。
The human ankle varies impedance and delivers net positive work during the stance period of walking. In contrast, commercially available ankle-foot prostheses are passive during stance, causing many clinical problems for transtibial amputees, including non-symmetric gait patterns, higher gait metabolism, and Poorer shock absorption. In this investigation, we develop and evaluate a myoelectric-driven, finite state controller for a powered ankle-foot prosthesis that modulates both impedance and power output during stance. The system employs both sensory inputs measured local to the external prosthesis, and myoelectric inputs measured from residual limb muscles. Using local prosthetic sensing, we first develop two finite state controllers to produce biomimetic movement patterns for level-ground and stair-descent gaits. We then employ myoelectric signals as control commands to manage the transition between these finite state controllers. To transition from level-ground to stairs, the amputee flexes the gastrocnemius muscle, triggering the Prosthetic ankle to plantar flex at terminal swing, and initiating the stair-descent state machine algorithm. To transition back to level-ground walking, the amputee flexes the tibialis anterior muscle, triggering the ankle to remain dorsiflexed at terminal swing, and initiating the level-ground state machine algorithm. As a preliminary evaluation of clinical efficacy, we test the device on a transtibial amputee with both the proposed controller and a conventional passive-elastic control. We find that the amputee can robustly transition between the finite state controllers through direct muscle activation, allowing rapid transitioning from level-ground to stair walking patterns. Additionally, we find that the proposed finite state controllers result in a more biomimetic ankle response, producing net propulsive work during level-ground walking and greater shock absorption during stair descent. The results of this study highlight the potential of prosthetic leg controllers that exploit neural signals to trigger terrain-appropriate, local prosthetic leg behaviors. (C) 2008 Elsevier Ltd. All rights reserved.