TY - GEN
T1 - A new robotic approach to characterize mechanical impedance and energetic passivity of the human ankle during standing
AU - Nalam, Varun
AU - Lee, Hyunglae
N1 - Funding Information:
This study was completed by the support of Virginia G. Piper Foundation and Ira A. Fulton Schools of Engineering at the Arizona State University.
Publisher Copyright:
© 2017 IEEE.
PY - 2017/9/13
Y1 - 2017/9/13
N2 - This paper presents the quantitative characterization of ankle impedance and ankle passivity during upright standing. A novel multi-axis robotic platform allows for the quantification of these neuromuscular properties in two degrees-of-freedom of the ankle, specifically, dorsiflexion-plantarflexion (DP) and inversion-eversion (IE). For the slow sinusoid perturbations of low frequencies ranging up to 1.5 Hz, ankle impedance was accurately approximated by stiffness and damping, while the contribution of inertia and reflex feedback was minimal. Ankle stiffness and damping were found to be highly direction dependent, being much higher in the DP than IE direction. Ankle stiffness linearly increased with co-contraction of ankle muscles. While the same trend was evident for ankle damping in the DP direction, no significant changes were observed in the IE direction. In addition, the ankle behavior was found to be highly dissipative in both DOFs over a wide range of muscle activation for young healthy subjects. Characterization results in this study would not only provide an insight into the functional contribution of the ankle to the control of postural balance but also add valuable information in the development of neuro-rehabilitation and assistive devices.
AB - This paper presents the quantitative characterization of ankle impedance and ankle passivity during upright standing. A novel multi-axis robotic platform allows for the quantification of these neuromuscular properties in two degrees-of-freedom of the ankle, specifically, dorsiflexion-plantarflexion (DP) and inversion-eversion (IE). For the slow sinusoid perturbations of low frequencies ranging up to 1.5 Hz, ankle impedance was accurately approximated by stiffness and damping, while the contribution of inertia and reflex feedback was minimal. Ankle stiffness and damping were found to be highly direction dependent, being much higher in the DP than IE direction. Ankle stiffness linearly increased with co-contraction of ankle muscles. While the same trend was evident for ankle damping in the DP direction, no significant changes were observed in the IE direction. In addition, the ankle behavior was found to be highly dissipative in both DOFs over a wide range of muscle activation for young healthy subjects. Characterization results in this study would not only provide an insight into the functional contribution of the ankle to the control of postural balance but also add valuable information in the development of neuro-rehabilitation and assistive devices.
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U2 - 10.1109/EMBC.2017.8037763
DO - 10.1109/EMBC.2017.8037763
M3 - Conference contribution
C2 - 29060804
AN - SCOPUS:85032175309
T3 - Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS
SP - 4123
EP - 4126
BT - 2017 39th Annual International Conference of the IEEE Engineering in Medicine and Biology Society
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 39th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2017
Y2 - 11 July 2017 through 15 July 2017
ER -