Caputo Joshua M, Collins Steven H
J Biomech Eng. 2014 Mar;136(3):035002. doi: 10.1115/1.4026225.
Robotic prostheses have the potential to significantly improve mobility for people with lower-limb amputation. Humans exhibit complex responses to mechanical interactions with these devices, however, and computational models are not yet able to predict such responses meaningfully. Experiments therefore play a critical role in development, but have been limited by the use of product-like prototypes, each requiring years of development and specialized for a narrow range of functions. Here we describe a robotic ankle-foot prosthesis system that enables rapid exploration of a wide range of dynamical behaviors in experiments with human subjects. This emulator comprises powerful off-board motor and control hardware, a flexible Bowden cable tether, and a lightweight instrumented prosthesis, resulting in a combination of low mass worn by the human (0.96 kg) and high mechatronic performance compared to prior platforms. Benchtop tests demonstrated closed-loop torque bandwidth of 17 Hz, peak torque of 175 Nm, and peak power of 1.0 kW. Tests with an anthropomorphic pendulum "leg" demonstrated low interference from the tether, less than 1 Nm about the hip. This combination of low worn mass, high bandwidth, high torque, and unrestricted movement makes the platform exceptionally versatile. To demonstrate suitability for human experiments, we performed preliminary tests in which a subject with unilateral transtibial amputation walked on a treadmill at 1.25 ms-1 while the prosthesis behaved in various ways. These tests revealed low torque tracking error (RMS error of 2.8 Nm) and the capacity to systematically vary work production or absorption across a broad range (from -5 to 21 J per step). These results support the use of robotic emulators during early stage assessment of proposed device functionalities and for scientific study of fundamental aspects of human-robot interaction. The design of simple, alternate end-effectors would enable studies at other joints or with additional degrees of freedom.
机器人假肢有潜力显著改善下肢截肢者的行动能力。然而，人类对与这些装置的机械交互会表现出复杂的反应，而计算模型尚无法有意义地预测此类反应。因此，实验在其开发过程中起着关键作用，但一直受到类产品原型使用的限制，每个原型都需要数年的开发时间，并且功能范围狭窄。在此，我们描述了一种机器人踝足假肢系统，它能够在人体实验中快速探索广泛的动态行为。该模拟器包括强大的外置电机和控制硬件、灵活的鲍登缆绳系链以及轻便的仪器化假肢，与之前的平台相比，实现了人体佩戴的低质量（0.96千克）和高机电性能的结合。台式测试表明，其闭环扭矩带宽为17赫兹，峰值扭矩为175牛米，峰值功率为1.0千瓦。使用拟人化摆“腿”进行的测试表明，系链的干扰很小，髋关节处小于1牛米。这种低佩戴质量、高带宽、高扭矩和无限制运动的组合使该平台具有非凡的通用性。为了证明其适用于人体实验，我们进行了初步测试，一名单侧胫骨截肢的受试者在跑步机上以1.25米/秒的速度行走，同时假肢以各种方式运行。这些测试显示出低扭矩跟踪误差（均方根误差为2.8牛米），并且能够在很宽的范围内（每步从-5到21焦耳）系统地改变功的产生或吸收。这些结果支持在对拟议的设备功能进行早期评估以及对人机交互基本方面进行科学研究时使用机器人模拟器。设计简单的替代末端执行器将能够在其他关节或具有更多自由度的情况下进行研究。
