A gravity balancing lower extremity exoskeleton is a simple mechanical device composed of rigid links, joints and springs, which is adjustable to the geo-metry and inertia of the leg of a human subject wearing it. This passive exoskeleton does not use any motors or controllers, yet can still unload the human leg joints of the gravity load over the full range of motion of the leg. The underlying principle of gravity balancing consists of two steps: Locate the combined system center of mass of the human leg and the exoskeleton, Add springs to the exoskeleton, one between the cen-ter of mass of the combined system and the fixed frame representing the trunk, the others within the links of the exoskeleton so that the potential energy of the combined system is invariant with configuration of the leg. Additionally, parameters of the exoskeleton can be changed to achieve a pres-cribed level of par-tial balancing, between 0-gravity and 1-gravity. The goals of this paper are as fol-lows: briefly review the theory for gravity balancing and present laboratory prototypes of gravity ba-lanced machines, describe the design of a lower extremity exoskeleton that was fabricated using this prin-ciple, and show the perfor-mance of the exoskeleton on both healthy human subjects and a stroke patient by comparison of leg muscle EMG recordings, joint range of motion, and measured joint torques. These results strongly suggest that human joints can be unloaded from gravity using these exoskeletons and the human joint range of motion can be significantly increased. Potential applications of gravity balancing exo-skeletons include:gait training of stroke patients, characterization of long-term effects of zero gravity on the human musculature, human performance augmentation during assembly tasks.

Категория: Научные статьи | Нет комментариев »

Комментарии