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

最先进的下肢假肢通常是无源装置，不向其使用者提供任何有源功率。 因此，截肢者在行走时必须消耗更多的能量。 假体的最新进展已经通过包括电池和马达以提供有功功率来解决这些缺点。 与传统的假肢不同，这些有源设备的软件需要根据每个人进行“调整”。 本项目将研究如何改善这一调整过程，从而提高人们使用动力假肢的性能。 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，研究人员还将研究使用一种计算机程序来自动化这一过程。 也就是说，计算机将重复测量行走性能，并将自动改变设备设置，直到确定最佳值。 所有这一切都发生在使用者带着假肢行走时。 结果可以积极影响约160万肢体丧失者的生活。 有了工作良好的动力假肢，截肢者可以走得更长、更自然。 这也可能有次要的健康益处，如心脏病的风险较小，或减少疼痛。该项目建立了确定动力假肢设备设置的客观性。 它将仔细量化控制器参数的影响，如功率大小和供电时间，对动力假肢的性能。 它将确定代谢努力，肌肉活动，运动学，动力学和主观反馈的措施。 所有研究都将在经胫骨截肢的个体中进行。 此外，研究人员还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”的真实的时间内实现这一点，研究人员将研究先进的信号处理和优化方法。 在这种情况下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。 这允许利用所有的代谢测量-甚至那些在达到稳态之前进行的测量。 这种技术大大加快了间接量热法的过程，并实现了自动调谐过程。 从结果中，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，以及与手动调整相比，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.