UNS: Development and Comparison of New Methods for Stabilizing Amputee Gait

1511177(柯林斯)在美国100多万截肢患者中，大约有一半人每年都会跌倒，通常是在走路的时候。这些跌倒往往会导致严重受伤，每年的医疗费用超过10亿美元。侧向运动在行走过程中最不稳定，特别是在不平坦的地形上，需要更积极的控制来保持平衡。令人惊讶的是，人们对影响侧向运动的假体特性如何影响平衡知之甚少。虽然机器人假肢已经改善了推进能力和能源成本，但这项技术尚未被用于提高稳定性或降低跌倒风险。该项目探索了使用机器人假肢控制侧向平衡的新方法，表征了假体参数对稳定性的影响，并建立了与平衡相关的性能的定量成本-收益关系。它将使人们对脚踝控制在人体平衡中的作用以及不稳定对步态和灵活性其他方面的影响有新的基本理解。该项目将开发技术，以降低跌倒几率，提高满意度，增强截肢患者的机动性，提高生活质量。可增强平衡性的主动、半主动和被动假体元件正在开发中，并根据关键尺寸量化它们的相对成本和收益，以促进合理的设计选择。这将提高医疗保健提供的效率，设备成本的增加将被与跌倒相关的伤害治疗成本的减少所抵消。这个项目发生在跨学科的教育环境中，博士、硕士和本科生与临床专家互动，并在开发解决残疾问题的技术方面获得经验。这种令人信服的技术应用改善了人们的福祉，吸引了新的科学和工程参与者，增加了对女性和少数族裔学生的招生。一个私营部门的合作伙伴正在帮助解决商业翻译问题。该项目建立了稳定截肢者步态的新技术，并比较了实施成本与平衡稳定性、新陈代谢能量使用和平衡信心方面的相关好处。实验利用了一种先前开发的系留踝足假体，该假体在足底屈曲和内翻两个方向上都有高保真的扭矩控制。这一工具能够对假体功能和控制对人体性能的影响进行新的快速、可控的测试。该项目团队包括经验丰富的医生、修复师、企业家和研究人员，以确保医疗、临床、商业和科学方面的相关性。该项目的主要目标是：目标1：开发新的假肢控制方法来稳定截肢者的步态。几种有前途的技术正在单侧胫骨外侧截肢者的实验中得到检验，包括：i)每步一步基于内侧质心速度的踝关节推出功调制，这是研究人员先前在对非残疾受试者的模拟和实验中建立的一项技术；ii)每步一次的内翻-外翻扭矩调制，预计将进一步增强侧向平衡；iii)每步一次的表面匹配，预计将缓解地面不规则的影响；以及iv)优化的内翻-外翻刚度，预计将以低实施成本适度改善平衡。这些方法分别在单独的测试中进行检查，然后进行比较。参与者受到不规则地形的影响，这对截肢者来说是一个常见的平衡挑战。通过步态可变性、代谢率、肌肉活动和自我报告的信心和偏好来衡量表现。目标2：稳定技术的成本效益分析。主动控制技术，如推力做功调制，需要昂贵的大功率电机和大型电池。半主动技术，如表面匹配，可以用更小、更便宜的驱动方案来实现。实施成本的估计与实验测量的收益相结合，以确定每种结果的成本和收益之间的关系，并确定帕累托最优假体特征。

1511177(Collins)About half of the one million people in the United States with lower-limb amputation experience a fall each year, usually during walking. These falls often result in serious injury, with annual health care costs of over one billion dollars. Side-to-side motions are least stable during walking, especially on uneven terrain, and require more active control for balance. Surprisingly, little is known about how balance is affected by prosthesis properties that influence side-to-side motions. While robotic prostheses have improved propulsion and energy cost, this technology has not yet been used to improve stability or reduce fall risk. This project explores new approaches to the control of side-to-side balance using robotic prostheses, characterizes the effects of prosthesis parameters on stability, and establishes quantitative cost-benefit relationships for balance-related performance. It will yield new fundamental understanding of the role of ankle control in human balance and of the impact of instability on other aspects of gait and mobility. The project will develop technologies that lead to reduced fall rates, increased satisfaction and enhanced mobility for individuals with amputation, improving quality of life. Active, semi-active and passive prosthesis elements that enhance balance are being developed and their relative costs and benefits quantified along key dimensions, facilitating rational design choices. This will lead to increased efficiency in health care delivery, with increases in device cost being offset by reductions in costs for treating fall-related injuries. This project takes place in an interdisciplinary educational setting, in which doctoral, Master's and undergraduate students interact with clinical experts and gain experience in developing technologies to address disability. This compelling application of technology to improve people's well-being attracts new participants to science and engineering, enhancing the recruitment of female and minority students. A private-sector partner is helping to address commercial translation.This project establishes new techniques for stabilizing amputee gait and compares implementation costs to balance-related benefits in terms of stability, metabolic energy use, and balance confidence. Experiments utilize a previously-developed, tethered ankle-foot prosthesis with high-fidelity torque control in both plantarflexion and inversion-eversion directions. This tool enables a new class of rapid, well-controlled tests of the effects of prosthesis features and control on human performance. The project team includes experienced physicians, prosthetists, entrepreneurs and researchers to ensure medical, clinical, commercial and scientific relevance. The primary goals of the project are: Goal 1: Develop new prosthesis control methods to stabilize amputee gait. Several promising techniques are being examined in experiments with unilateral trans-tibial amputees, including: i) once-per-step ankle push-off work modulation based on medial-lateral center of mass velocity, a technique the investigators previously established in simulations and experiments with non-disabled subjects; ii) once-per-step inversion-eversion torque modulation, expected to further enhance side-to-side balance; iii) once-per-step surface matching, expected to mitigate the effects of ground irregularities; and iv) optimized inversion-eversion stiffness, expected to modestly improve balance at low implementation cost. These methods are independently examined in separate tests and then compared. Participants are subjected to irregular terrain, a common balancing challenge for amputees. Performance is measured in terms of gait variability, metabolic rate, muscle activity, and self-reported confidence and preference. Goal 2: Cost-benefit analysis of stabilization techniques. Active control techniques, such as push-off work modulation, require expensive, high-power motors and large batteries. Semi-active techniques, such as surface matching, could be implemented with smaller, less-expensive actuation schemes. Estimates of implementation costs are combined with experimentally measured benefits to determine relationships between cost and benefit for each outcome and identify Pareto-optimal prosthesis characteristics.