A computational framework to study neural-structural interactions in human walking

Neuroscientists researching locomotion take a top-down approach by elucidating high- level cortical control circuits. In contrast, biomechanists prefer to focus on structural and mechanical aspects of the legged movement apparatus. We posit that studying interplay between neural co-ordination and legged biomechanics can yield crucial insight into (a) motor control and (b) human leg morphology. Physiological facts indicate that muscle actuator state (activation, length and velocity) is key to this neural-structural interplay. Here we present a novel model-based framework to resolve individual muscle state and describe neural-structural interactions in normal gait. We solve the inverse problem of using kinematic, kinetic and electro-myographic data recorded on healthy humans during level-ground,self-selected speed walking to estimate state of three major ankle muscles. Our approach comprises of two steps. First, we estimate neurally-controlled muscle activity from EMG data by building on statistical and mechanistic methods in the literature. Second, we perform a system ID on a mechanistic (Hill-type) model of the three muscles to nd tendon morpho- logical parameters governing evolution of muscle length and velocity. We implement the parameter identication as an optimization based on the hypothesis that neural control and lower limb morphology have co-evolved for optimal metabolic economy of natural walking.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2010

Author dc:creator

• Krishnaswamy, Pavitra

Advisor dc:contributor.advisor

• Hugh Herr and Emery N. Brown.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/57539

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/57539