Feedback equilibrium control during human standing

A. Alexandrov, A. Frolov, F. Horak, P. Carlson-Kuhta, S. Park

Research output: Contribution to journalArticlepeer-review

232 Scopus citations


Equilibrium maintenance during standing in humans was investigated with a 3-joint (ankle, knee and hip) sagittal model of body movement. The experimental paradigm consisted of sudden perturbations of humans in quiet stance by backward displacements of the support platform. Data analysis was performed using eigenvectors of motion equation. The results supported three conclusions. First, independent feedback control of movements along eigenvectors (eigenmovements) can adequately describe human postural responses to stance perturbations. This conclusion is consistent with previous observations (Alexandrov et al., 2001b) that these same eigenmovements are also independently controlled in a feed-forward manner during voluntary upper-trunk bending. Second, independent feedback control of each eigenmovement is sufficient to provide its stability. Third, the feedback loop in each eigenmovement can be modeled as a linear visco-elastic spring with delay. Visco-elastic parameters and time-delay values result from the combined contribution of passive visco-elastic mechanisms and sensory systems of different modalities.

Original languageEnglish (US)
Pages (from-to)309-322
Number of pages14
JournalBiological Cybernetics
Issue number5
StatePublished - Nov 2005

ASJC Scopus subject areas

  • Biotechnology
  • Computer Science(all)


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