Watching quiet human stance to shake off its straitjacket

The single-inverted pendulum (SIP) model is still the paradigm describing dynamics and control of quiet human stance in the sagittal plane. We used two methods to verify this paradigm. First, in an experimental approach we acquired kinematic data of both legs of ten subjects at high spatial resoluti...

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Bibliographic Details
Published inArchive of applied mechanics (1991) Vol. 81; no. 3; pp. 283 - 302
Main Authors Günther, Michael, Müller, Otto, Blickhan, Reinhard
Format Journal Article
LanguageEnglish
Published Berlin/Heidelberg Springer-Verlag 01.03.2011
Subjects
Classical Mechanics
Computer simulation
Dipping
Dynamics
Engineering
Human
Mathematical analysis
Mathematical models
Original
Pendulums
Theoretical and Applied Mechanics
Torque
Posture control
Inverted pendulum
Biomechanical model
Inverse dynamics
Double pendulum
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Summary:The single-inverted pendulum (SIP) model is still the paradigm describing dynamics and control of quiet human stance in the sagittal plane. We used two methods to verify this paradigm. First, in an experimental approach we acquired kinematic data of both legs of ten subjects at high spatial resolution while quietly standing on two force platforms. We calculated all leg joint angles, the belonging joint torques using inverse dynamics and estimates of joint stiffnesses. Some linear correlations and regressions of both local (joint) and global (COM, COP: centre of mass respectively pressure) variables predicted by the SIP model were investigated. All three verification criteria applied to mean values extracted from experimental data revealed that the SIP is not a valid model for quiet human stance. As a second method, we used computer synthesis to demonstrate that a double-inverted pendulum (DIP) model enters a stable attractor when just the “hip” joint torque is regulated, whereas no torque is applied to the “ankle” joint. Here, angle and torque fluctuations are necessary because such a DIP strategy is of inevitable dynamic character. The two predicted eigenfrequencies of this regulated DIP model approximate the upper and lower limits of the main part of measured power spectra of quiet human stance. We suggest this dynamic necessity to be representative of the biological constraints under which a mechanically unstable inverted multi-segment chain must be stabilised.
Bibliography:ObjectType-Article-2
SourceType-Scholarly Journals-1
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ISSN:0939-1533
1432-0681
DOI:10.1007/s00419-010-0414-y