Stochastic estimation of the multi-variable mechanical impedance of the human ankle with active muscles

Mohammad A. Rastgaar, Patrick Ho, Hyunglae Lee, Hermano Igo Krebs, Neville Hogan

Research output: Chapter in Book/Report/Conference proceedingConference contribution

14 Scopus citations

Abstract

This article compares stochastic estimates of multi-variable human ankle mechanical impedance when ankle muscles were fully relaxed, actively generating ankle torque or co-contracting antagonistically. We employed Anklebot, a rehabilitation robot for the ankle, to provide torque perturbations. Muscle activation levels were monitored electromyographically and these EMG signals were displayed to subjects who attempted to maintain them constant. Time histories of ankle torques and angles in the Dorsi-Plantar flexion (DP) and Inversion-Eversion (IE) directions were recorded. Linear time-invariant transfer functions between the measured torques and angles were estimated for the Anklebot alone and when it was worn by a human subject, the difference between these functions providing an estimate of ankle mechanical impedance. High coherence was observed over a frequency range up to 30 Hz. The main effect of muscle activation was to increase the magnitude of ankle mechanical impedance in both DP and IE directions.

Original languageEnglish (US)
Title of host publicationASME 2010 Dynamic Systems and Control Conference, DSCC2010
Pages429-431
Number of pages3
DOIs
StatePublished - Dec 1 2010
EventASME 2010 Dynamic Systems and Control Conference, DSCC2010 - Cambridge, MA, United States
Duration: Sep 12 2010Sep 15 2010

Publication series

NameASME 2010 Dynamic Systems and Control Conference, DSCC2010
Volume1

Other

OtherASME 2010 Dynamic Systems and Control Conference, DSCC2010
CountryUnited States
CityCambridge, MA
Period9/12/109/15/10

ASJC Scopus subject areas

  • Control and Systems Engineering

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    Rastgaar, M. A., Ho, P., Lee, H., Krebs, H. I., & Hogan, N. (2010). Stochastic estimation of the multi-variable mechanical impedance of the human ankle with active muscles. In ASME 2010 Dynamic Systems and Control Conference, DSCC2010 (pp. 429-431). (ASME 2010 Dynamic Systems and Control Conference, DSCC2010; Vol. 1). https://doi.org/10.1115/DSCC2010-4224