Powered ankle-foot prostheses can often reduce the energy cost of walking by assisting with push-off. However, focus on providing mechanical work may lead to ignoring or exacerbating common issues with chronic pain, irritation, pressure ulcer development, and eventual osteoarthritis in persons with amputation. This paper presents the design and validation of a novel transtibial prosthesis informed by predictive biomechanical simulations of gait which minimize a combination of user effort and interaction loading from the prosthesis socket. From these findings, the device was designed with a non-biomimetic anterior-posterior translation degree of freedom with a 10 cm range of motion which is primarily position-controlled to change the alignment of the prosthetic foot with the residual limb. The system is both mobile and tethered, with the batteries, actuators, and majority of electronics located in a small backpack. Mechanical loads are transmitted through cables to the prosthesis, minimizing the distal mass carriage required. We measured torque and force sensing accuracy, open loop actuator performance, closed loop torque and position control bandwidth, and torque and position tracking error during walking. The system is capable of producing up to 160 N-m of plantarflexion torque and 394 N of AP translation force with a closed loop control bandwidth of about 7 Hz in both degrees of freedom. Torque tracking during walking was accurate within about 10 N-m but position tracking was substantially affected by phase lag, possibly due to cable slack in the bidirectional mechanism. The prototype was capable of replicating our simulated prosthesis dynamics during gait and offers useful insights into the advantages and the practical considerations of using predictive biomechanical simulation as a design tool for wearable robots.

翻译：动力踝足假肢通常能通过辅助推进来降低行走的能量消耗。然而，过度关注提供机械功可能导致忽视或加剧截肢者常见的慢性疼痛、刺激、压力性溃疡形成及最终骨关节炎等问题。本文提出了一种新型经胫骨假肢的设计与验证，该设计基于步态的预测性生物力学仿真，旨在最小化使用者自身努力与假肢接受腔交互负荷的综合影响。基于这些发现，该装置设计了一个非仿生的前后平移自由度（运动范围为10厘米），主要通过位置控制来改变假足与残肢的对齐关系。该系统兼具移动与系留特性，电池、执行器及大部分电子设备位于小型背包中。机械载荷通过缆线传递至假肢，从而最大限度地减少了远端所需承载的质量。我们测量了扭矩与力传感精度、开环执行器性能、闭环扭矩与位置控制带宽，以及行走过程中的扭矩与位置跟踪误差。该系统能够产生高达160牛·米的跖屈扭矩和394牛的前后平移力，且两个自由度的闭环控制带宽均约为7赫兹。行走过程中的扭矩跟踪精度约为10牛·米以内，但位置跟踪受相位滞后影响显著，这可能是双向机构中缆线松弛所致。该原型机能够在步态中复现仿真假肢动力学特性，并为将预测性生物力学仿真作为可穿戴机器人设计工具的优势与实际考量提供了有价值的见解。