Proportional Joint-Moment Control for Instantaneously Adaptive Ankle Exoskeleton Assistance
Proportional Joint-Moment Control for Instantaneously Adaptive Ankle Exoskeleton Assistance
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DOI：
10.1109/tnsre.2019.2905979
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发表时间：
2019-04-01
影响因子：
4.9
通讯作者：
Lerner, Zachary F.
中科院分区：
文献类型：
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作者：
Gasparri, Gian Maria;Luque, Jason;Lerner, Zachary F.
必须控制用于改善神经肌肉障碍患者自由生活活动能力的下肢外骨骼，以提供适应日常生活中遇到的不同运动条件的帮助，包括以不同的速度和不同的地形行走。本文的目的是设计和建立一种脚踝外骨骼控制策略的临床可行性，该策略可以即时和适当地调整辅助，以适应可变步行过程中不断变化的生物力学需求。为了实现这一目标，我们开发了一种比例关节力矩控制策略，根据踝关节力矩的瞬时估计来指定辅助，并进行了基于实验室的可行性研究。四名神经运动受损的个体和一名未受损的个体完成了外骨骼辅助的慢速和快速步态转换任务，其中包括步态启动和改变行走速度。我们发现，控制器在瞬间提供与踝关节力矩成正比的外骨骼辅助是有效的，平均均方根误差不到14%。我们还进行了三个对象的初步调查，以确定比例关节力矩控制器改善步行经济的能力。在两名脑瘫患者和一名健康个体中进行评估，与佩戴外骨骼不辅助相比，比例控制跑步机和地面步行时运输的代谢成本提高了17%-27%。这些初步发现支持继续研究比例关节力矩控制，以帮助在真实世界环境中行走的神经肌肉障碍患者。
Lower-limb exoskeletons used to improve free-living mobility for individuals with neuromuscular impairment must be controlled to prescribe assistance that adapts to the diverse locomotor conditions encountered during daily life, including walking at different speeds and across varied terrain. The goal of this paper is to design and establish clinical feasibility of an ankle exoskeleton control strategy that instantly and appropriately adjusts assistance to the changing biomechanical demand during variable walking. To accomplish this goal, we developed a proportional joint-moment control strategy that prescribes assistance as a function of the instantaneous estimate of the ankle joint moment and conducted a laboratory-based feasibility study. Four individuals with neuromotor impairment and one unimpaired individual completed exoskeleton-assisted slow and fast gait transition tasks that involved gait initiation and changing walking speed. We found that the controller was effective in instantaneously prescribing exoskeleton assistance that was proportional to the ankle moment with less than 14% root-mean-square error, on average. We also performed a three-subject pilot investigation to determine the ability of the proportional joint-moment controller to improve walking economy. Evaluated in two individuals with cerebral palsy and one unimpaired individual, metabolic cost of transport improved 17-27% during treadmill and over-ground walking with proportional control compared with wearing the exoskeleton unassisted. These preliminary findings support the continued investigation of proportional joint-moment control for assisting individuals with neuromuscular disabilities during walking in real-world settings.