Gravity-balancing leg orthosis and its performance evaluation
Gravity-balancing leg orthosis and its performance evaluation
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DOI：
10.1109/tro.2006.882928
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发表时间：
2006-12-01
影响因子：
7.8
通讯作者：
Rudolph, Katherine
中科院分区：
文献类型：
--
作者：
Banala, Sai K.;Agrawal, Sunil K.;Rudolph, Katherine
在本文中，我们提出了一种装置，以帮助偏瘫患者步行，减少或消除重力的影响。该装置的设计包括以下特征：1）它是无源的，即，它不包括电动机或致动器;而是仅由连杆和弹簧组成; 2）它是安全的并且具有简单的患者-机器接口以适应对象的几何形状和惯性的变化。在文献中已经提出了许多方法来对机器进行重力平衡。在这里，我们使用混合方法来实现重力平衡的人腿在其运动范围。在混合方法中，使用机构来首先定位人体、肢体和矫形器的质心。然后添加弹簧，以便系统在每个配置中都保持重力平衡。为了定量评价该装置的性能，收集并分析了参与腿部运动的关键肌肉的肌电图（EMG）数据。进一步的实验涉及腿部抬起和行走任务，其中来自编码器和力-扭矩传感器的数据用于计算关节扭矩。这些实验在五名健康受试者和一名中风患者身上进行。结果表明，在静态髋关节和膝关节屈曲时，股直肌和腘绳肌的EMG活动分别减少了75%。对于抬腿任务，髋关节静态定位的平均扭矩减少了66.8%，膝关节减少了47.3%;然而，如果我们包括抬腿任务的瞬时部分，髋关节的平均扭矩减少了61.3%，膝关节的平均扭矩增加了2.7%。在步行实验中，对髋关节和膝关节的运动范围有积极的影响，特别是对于中风患者：髋关节的运动范围增加了45%，膝关节增加了85%。我们相信，这种矫形器可以潜在地用于设计中风患者的康复方案。
In this paper, we propose a device to assist persons with hemiparesis to walk by reducing or eliminating the effects of gravity. The design of the device includes the following features: 1) it is passive, i.e., it does not include motors or actuators; but is only composed of links and springs; 2) it is safe and has a simple patient-machine interface to accommodate variability in geometry and inertia of the subjects. A number of methods have been proposed in the literature to gravity-balance a machine. Here, we use a hybrid method to achieve gravity balancing of a human leg over its range of motion. In the hybrid method, a mechanism is used to first locate the center of mass of the human, limb and the orthosis. Springs are then added so that the system is gravity-balanced in every configuration. For a quantitative evaluation of the performance of the device, electromyographic (EMG) data of the key muscles, involved in the motion of the leg, were collected and analyzed. Further experiments involving leg-raising and walking tasks were performed, where data from encoders and force-torque sensors were used to compute joint torques. These experiments were performed on five healthy subjects and a stroke patient. The results showed that the EMG activity from the rectus femoris, and hamstring muscles with the device was reduced by 75%, during static hip and knee flexion, respectively. For leg-raising tasks, the average torque for static positioning was reduced by 66.8% at the hip joint and 47.3% at the knee joint; however, if we include the transient portion of the leg-raising task, the average torque at the hip was reduced by 61.3%, and at the knee was increased by 2.7% at the knee joints. In the walking experiment, there was a positive impact on the range of movement at the hip and knee joints, especially for the stroke patient: the range of movement increased by 45% at the hip joint and by 85% at the knee joint. We believe that this orthosis can be potentially used to design rehabilitation protocols for patients with stroke.