Optimizing the Control of Powered Prostheses with the Human Body in the Loop

最先进的假肢通常是无源设备，不向使用者提供任何有源电力。因此，截肢的人在走路时必须消耗更多的能量。假体的最新进展通过包括电池和马达来提供有源动力，解决了这些缺点。与传统的假肢不同，这些主动设备的软件需要根据每个人的需要进行调整。这个项目将研究如何改进这一调整过程，从而提高使用动力假体的人的表现。为此，研究小组将系统地改变设备设置，同时测量行走所需的能量和由此产生的行走运动的对称性。此外，研究人员将调查计算机程序的使用情况，该程序将使这一过程自动化。也就是说，计算机将重复测量行走性能，并自动更改设备设置，直到确定最佳值。所有这些都是在使用者戴着假肢行走时发生的。这一结果可以对大约160万失去肢体的人的生活产生积极影响。有了工作良好的动力假体，截肢者可以走得更远，走得更自然。这也可能有次要的健康益处，如较小的心脏病风险，或减少疼痛。该项目在确定电动假体的设备设置方面建立了客观性。它将仔细量化控制器参数，如功率大小和供电时间对电动假体性能的影响。它将决定代谢努力、肌肉活动、运动学、动力学和主观反馈的衡量标准。所有研究都将以经胫骨截肢患者为研究对象。此外，研究人员将研究一种优化算法的潜力，该算法通过最小化代谢努力来自动找到控制器参数。为了在人体处于“循环中”的情况下实时实现这一点，研究人员将研究先进的信号处理和优化方法。在这方面的关键创新之一是明确考虑到每个个体受试者的代谢动力学。这允许利用所有的新陈代谢测量--甚至那些在达到稳定状态之前进行的测量。这项技术极大地加快了间接量热法的进程，并使自动调整过程成为可能。根据结果，人们将能够确定如何适当地识别动力假体的最佳参数设置，以及与手动调谐相比，它们提供了多大的改进。

State-of-the-art lower-limb prostheses are generally passive devices that do not provide any active power to their user. As a consequence, people with amputations must expend substantially more energy when walking. Recent advances in prostheses have addressed these shortcomings by including batteries and motors to provide active power. Unlike traditional prostheses, the software of these active devices needs to be "tuned" to each person. This project will investigate ways to improve this tuning process and thus enhance the performance of people using powered prostheses. To this end, the study team will systematically change device settings while measuring the energy needed to walk and the symmetry of the resulting walking motion. Additionally, the researchers will investigate the use of a computer program that will automate this process. That is, the computer will take repeated measurements of walking performance and will automatically change device settings until optimal values are determined. All this happens while the user is walking with the prosthesis. The result can positively affect the lives of about 1.6 million people that are living with limb loss. With a well working powered prosthesis, amputees can walk longer and in a more natural fashion. This may also have secondary health benefits, such as a smaller risk of heart disease, or a reduction in pain.This project establishes objectivity in the determination of device settings for powered prostheses. It will carefully quantify the influence of controller parameters, such as power magnitude and the time at which power is supplied, onto the performance of powered prostheses. It will determine measures of metabolic effort, muscle activity, kinematics, kinetics, and subjective feedback. All studies will be conducted with individuals with transtibial amputation. In addition, the researchers will investigate the potential of an optimization algorithm that automatically finds controller parameters through the minimization of metabolic effort. To achieve this in real time with the human body being "in the loop," the researchers will investigate advanced methods for signal processing and optimization. One of the key innovations in this context is to explicitly take into account the metabolic dynamics of each individual subject. This allows making use of all the metabolic measurements -- even those taken before steady-state is reached. This technique greatly accelerates the process of indirect calorimetry and enables the automated tuning process. From the result, one will be able to determine how to appropriately identify optimal parameter settings of powered prostheses and how much improvement they provide compared to manual tuning.