Biomechanical Effects of Stiffness in Parallel With the Knee Joint During Walking

The human knee behaves similarly to a linear torsional spring during the stance phase of walking with a stiffness referred to as the knee quasi-stiffness. The spring-like behavior of the knee joint led us to hypothesize that we might partially replace the knee joint contribution during stance by uti...

Full description

Saved in:
Bibliographic Details
Published in:IEEE transactions on biomedical engineering 2015-10, Vol.62 (10), p.2389-2401
Main Authors: Shamaei, Kamran, Cenciarini, Massimo, Adams, Albert A., Gregorczyk, Karen N., Schiffman, Jeffrey M., Dollar, Aaron M.
Format: Article
Language:English
Subjects:
Adolescent
Adult
Biomechanical Phenomena - physiology
Equipment Design
Exoskeleton Device
Exoskeletons
Female
human walking
Humans
Joints
Knee
knee biomechanics
Knee Joint - physiology
Legged locomotion
Legs
lower extremity exoskeleton
Male
Mathematical model
Orthotic Devices
Parallel stiffness
quasi-passive mechanism
Springs
variable-stiffness
Walking - physiology
Young Adult
Citations: Items that this one cites
Items that cite this one
Online Access:Request full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The human knee behaves similarly to a linear torsional spring during the stance phase of walking with a stiffness referred to as the knee quasi-stiffness. The spring-like behavior of the knee joint led us to hypothesize that we might partially replace the knee joint contribution during stance by utilizing an external spring acting in parallel with the knee joint. We investigated the validity of this hypothesis using a pair of experimental robotic knee exoskeletons that provided an external stiffness in parallel with the knee joints in the stance phase. We conducted a series of experiments involving walking with the exoskeletons with four levels of stiffness, including 0%, 33%, 66%, and 100% of the estimated human knee quasi-stiffness, and a pair of joint-less replicas. The results indicated that the ankle and hip joints tend to retain relatively invariant moment and angle patterns under the effects of the exoskeleton mass, articulation, and stiffness. The results also showed that the knee joint responds in a way such that the moment and quasi-stiffness of the knee complex (knee joint and exoskeleton) remains mostly invariant. A careful analysis of the knee moment profile indicated that the knee moment could fully adapt to the assistive moment; whereas, the knee quasi-stiffness fully adapts to values of the assistive stiffness only up to ~80%. Above this value, we found biarticular consequences emerge at the hip joint.
ISSN:0018-9294
1558-2531
DOI:10.1109/TBME.2015.2428636