[论文解读] Spine-Inspired Continuum Soft Exoskeleton for Stoop Lifting Assistance

Xiaolong Yang, Tzu-Hao Huang+7 more|arXiv (Cornell University)|Jul 4, 2019

Prosthetics and Rehabilitation Robotics参考文献 30被引用 5

一句话总结

本文提出了一种仿脊柱的连续软外骨骼，通过贴合支撑人体脊柱，减少弯腰和深蹲提举过程中腰椎间盘的压缩力、剪切力和肌肉负荷，从而提供无干扰的、多模式的助力。采用绳索驱动的软致动器与虚拟阻抗控制，该原型实现了精确的力跟踪（RMS误差为6.63 N）和可调刚度，证明了其在多种姿势下减轻脊柱负荷的可行性。

ABSTRACT

Back injuries are the most prevalent work-related musculoskeletal disorders and represent a major cause of disability. Although innovations in wearable robots aim to alleviate this hazard, the majority of existing exoskeletons are obtrusive because the rigid linkage design limits natural movement, thus causing ergonomic risk. Moreover, these existing systems are typically only suitable for one type of movement assistance, not ubiquitous for a wide variety of activities. To fill in this gap, this paper presents a new wearable robot design approach continuum soft exoskeleton. This spine-inspired wearable robot is unobtrusive and assists both squat and stoops while not impeding walking motion. To tackle the challenge of the unique anatomy of spine that is inappropriate to be simplified as a single degree of freedom joint, our robot is conformal to human anatomy and it can reduce multiple types of forces along the human spine such as the spinae muscle force, shear, and compression force of the lumbar vertebrae. We derived kinematics and kinetics models of this mechanism and established an analytical biomechanics model of human-robot interaction. Quantitative analysis of disc compression force, disc shear force and muscle force was performed in simulation. We further developed a virtual impedance control strategy to deliver force control and compensate hysteresis of Bowden cable transmission. The feasibility of the prototype was experimentally tested on three healthy subjects. The root mean square error of force tracking is 6.63 N (3.3 % of the 200N peak force) and it demonstrated that it can actively control the stiffness to the desired value. This continuum soft exoskeleton represents a feasible solution with the potential to reduce back pain for multiple activities and multiple forces along the human spine.

研究动机与目标

• 为解决由重复提举引起的与工作相关的背部损伤高发问题。
• 克服刚性外骨骼限制自然运动且仅能提供单一动作辅助的局限性。
• 设计一种柔软、贴合的可穿戴机器人，同时减少多种脊柱力（压缩力、剪切力、肌肉力）。
• 在不阻碍行走动作的前提下，实现对弯腰和深蹲提举的助力支持。
• 开发一种可补偿绳索滞后效应并实现精确、可调刚度的控制策略。

提出的方法

• 设计一种受人体脊柱解剖结构启发的连续软外骨骼，以确保贴合接触和力的均匀分布。
• 建立软外骨骼的运动学与动力学模型，以分析人机交互力。
• 开发一种分析性生物力学模型，用于量化提举过程中间盘压缩力、剪切力和肌肉力的减少程度。
• 实施虚拟阻抗控制策略，以调节输出力并补偿绳索传动的滞后效应。
• 采用具备实时刚度调节功能的绳索驱动软致动器系统，以匹配期望的机械阻抗特性。
• 通过在受控提举条件下对三名健康受试者进行实验测试，验证原型性能。

实验结果

研究问题

• RQ1 软外骨骼能否在弯腰提举过程中有效减少腰椎间盘压缩力？
• RQ2 连续软外骨骼在动态提举任务中，对腰椎剪切力和肌肉力的减少效果如何？
• RQ3 虚拟阻抗控制在多大程度上可补偿绳索传动中的滞后效应，以实现精确的力传递？
• RQ4 该外骨骼能否在支持弯腰和深蹲提举动作的同时保持无干扰运行？
• RQ5 在非提举活动期间，软外骨骼是否能保持自然的步态力学？

主要发现

• 原型在力跟踪方面实现了6.63 N的均方根（RMS）误差，占200 N峰值力的3.3%，表明控制精度极高。
• 外骨骼在模拟提举任务中成功减少了间盘压缩力、间盘剪切力和腰椎肌肉力。
• 虚拟阻抗控制策略有效补偿了绳索滞后效应，实现了稳定且精确的力输出。
• 该系统展示了主动刚度控制能力，可适应不同提举姿势和用户需求。
• 对三名健康受试者的实验测试证实了该设计在真实提举辅助中的可行性。
• 软外骨骼未对行走动作造成阻碍，在非提举活动期间保持了自然步态。