新型假脚通过可调对齐减少残肢压力,兼顾动力助行与舒适性。
A Sagittal Planar Ankle-Foot Prosthesis with Powered Plantarflexion and Socket Alignment
- 基于生物力学仿真优化设计,采用前后10厘米移动自由度调节足部对齐
- 可输出160牛·米跖屈力矩和394牛前向力,闭环控制带宽达7赫兹
- 轻量化背包供电,电缆传力减少远端质量,适合长期穿戴研究
动力踝足假肢可通过推进辅助降低行走能耗。但过度关注机械功输出可能加剧截肢者常见的慢性疼痛、皮肤刺激、压疮及骨关节炎问题。本文提出一种基于步态生物力学仿真优化的新型胫骨截肢假肢设计,旨在最小化用户努力与假肢接受腔交互负荷的综合影响。据此设计了非仿生的前后10厘米移动自由度,主要由位置控制实现足部与残肢对齐调整。系统兼具便携与有线两种模式,电池、驱动器及多数电子元件置于小型背包中,通过缆绳传输机械载荷,减少远端质量。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,以及行走中的扭矩与位置跟踪误差。系统最大可输出160牛·米跖屈力矩和394牛前向力,两个自由度闭环控制带宽均约7赫兹。行走中扭矩跟踪误差约10牛·米,但位置跟踪受相位滞后显著影响,可能源于双向机构中的缆绳松弛。原型能复现仿真所得步态动力学,为利用预测生物力学仿真作为可穿戴机器人设计工具提供了实用洞见。
原文摘要 · Abstract (English)
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.
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