User-Controlled Variable Stiffness Prosthesis to Improve Amputee Balance

 描述(由申请人提供)： 项目摘要(公共摘要)许多截肢者在行走时很难保持平衡，特别是在需要对地形或表面条件的变化做出快速反应的现实情况下。可以肯定的是，截肢者(和其他人)可能会因为无数的原因以各种各样的方式摔倒。表面意外滑动(例如，由于表面上的冰、油或其他液体)是一种很难想象可以防止失去平衡的假肢干预的跌倒类型。踩在不平坦的地形上则是另一回事，我们建议使用一种新颖的假肢来帮助恢复平衡。四分之一的室外瀑布是以侧向(内侧)方向发生的，那里存在着各种各样的不平坦的地形。对于下肢截肢者来说，在崎岖的地形上保持平衡可能尤其困难，因为他们缺乏补偿所需的脚踝肌肉，而且他们的假肢是被动的、弹性的装置，属性不能改变或适应。本研究的目的是通过为下肢截肢者提供一种能够响应他们的运动意图并适应地形变化的优化假体来改善他们的平衡。为了解决资深截肢者面临的这一重要问题，我们已经开发了一个先进的计算机建模和仿真框架，我们将使用该框架来确定最佳的脚踝特性，以便在不平坦的地形上行走一步后，最大限度地恢复平衡。我们还制造了第一代具有可变冠状面踝关节硬度的假体，并在截肢者的帮助下对其进行了测试，截肢者在一种新型的仪器化走道上行走，这种走道在不平坦的地形上重复了一步。我们的初步测试结果表明，不同的冠状面踝关节僵硬会影响截肢者如何控制他们的平衡。我们提出的研究有三个具体目标：(1)确定最大限度地恢复平衡的与地形相关的冠状踝关节特性。我们建议建立一个人体在不平坦地形上行走的三维双足肌肉骨骼模型，并用它来回答一个关键问题：在不平坦地形上行走一步后，使平衡恢复最大化的最佳冠状平面刚度是多少？(2)识别用户在不平坦地形上行走前的运动意图。我们建议对佩戴我们第一代假体的胫骨截肢者进行人体实验(n=20)。受试者将被要求在我们的仪表式人行道上行走，该人行道在不平坦的地形上重复单步行走，同时我们测量他们的运动意图(表面肌电图)。利用实验结果，我们将开发和测试三种算法来预测不平坦地形上的步长。我们假设这三种算法的精确度会有所不同。我们将使用结果来指定控制律，该控制律最好地预测在不平坦的地形上的步数，以用于我们的新型假肢。(3)确定与截肢者规定的假肢相比，一种为平衡恢复而优化并由用户运动意图控制的新型假体是否可以改善从凹凸不平的地形上的台阶恢复。为了实现这一目标，我们建议建立第二代假体，结合特定目标1和2的结果，以及从我们的第一代假体中学到的教训。然后，我们建议对经胫骨截肢者(n=20)进行一项人体实验，以测量他们在不平坦地形上行走一步后的平衡恢复情况。我们推测，与截肢者规定的假肢相比，我们的新型假体在不平坦的地形上行走一步后，将改善平衡的恢复。扩大退伍军人截肢者可以自信地行走的范围是退伍军人管理局应该做的事情：走在推动截肢者护理的假肢技术和处方实践的前沿。

 DESCRIPTION (provided by applicant): Project Summary (Public Abstract) Many lower limb amputees have difficulty maintaining balance while walking, especially in real-world situations that require quick responses to changes in terrain or surface conditions. To be certain, amputees (and others) can fall in a myriad of ways for a myriad of reasons. Unexpected slipping on a surface (e.g., due to ice, oil or other liquids on the surface) is an example of a class of falls where it is difficult to imagine a prosthetic intervention that might prevent loss of balance. Stepping on uneven terrain is a different class where we suggest a novel prosthesis might aid in balance recovery. A quarter of outdoor falls, where a wide variety of uneven terrains exist, occur in a sideways (mediolateral) direction. Maintaining balance when stepping on uneven terrain can be particularly difficult for lower limb amputees because they lack the foot-ankle muscles needed to compensate and their prostheses are passive, elastic devices whose properties cannot change or adapt. The purpose of this research is to improve the balance of lower limb amputees by providing them with an optimized prosthesis that can respond to their motor intentions and adapt to changes in terrain. To address this important issue faced by Veteran lower limb amputees, we have already developed an advanced computer modeling and simulation framework, which we will use to identify the optimal ankle properties that maximize balance recovery after a step on uneven terrain. We have also built a first generation prosthesis with variable coronal plane ankle stiffness and tested it with the help of amputees walking on a novel instrumented walkway that replicates a step on uneven terrain. The results of our preliminary tests suggest that varying coronal plane ankle stiffness can influence how an amputee controls their balance. Our proposed research has three specific aims: (1) To identify terrain-dependent coronal ankle properties that maximize balance recovery. We propose to develop a three-dimensional bipedal musculoskeletal model of human walking on uneven terrain and use it to answer a key question: What is the optimal coronal plane stiffness that maximizes balance recovery after a step on uneven terrain? (2) To identify user motor intentions before a step on uneven terrain. We propose to conduct a human subject experiment (n=20) with transtibial amputees wearing our first generation prosthesis. Subjects will be asked to walk on our instrumented walkway that replicates a single step on uneven terrain while we measure their motor intentions (surface electromyography). Using the experimental results, we will develop and test three algorithms to predict the step on uneven terrain. We hypothesize that there will be a difference in accuracy among the three algorithms. We will use the results to specify a control law that best predicts a step on uneven terrain for use with our novel prosthesis. (3) Determine if a novel prosthesis optimized for balance recovery and controlled by user motor intentions can improve the recovery from a step on uneven terrain when compared to the amputee's as- prescribed prosthesis. To achieve this aim, we propose to build a second generation prosthesis that incorporates the results from Specific Aims 1 and 2, as well as the lessons learned from our first generation prosthesis. We then propose to conduct a human subject experiment with transtibial amputees (n=20) that will measure their balance recovery after a step on uneven terrain. We hypothesize that our novel prosthesis will improve the recovery of balance after a step on uneven terrain when compared to the amputee's as-prescribed prosthesis. Expanding the terrain over which Veteran amputees can confidently walk is where the VA should be: at the forefront of prosthetic technology and prescription practice that advances amputee care.