Estimating ankle torque and dynamics of the stabilizing mechanism

Estimating ankle torque and dynamics of the stabilizing mechanism: No need for horizontal ground reaction forces

Schut, I.M. (TU Delft Biomechatronics & Human-Machine Control)
Pasma, J.H. (TU Delft Biomechatronics & Human-Machine Control; Haga Hospital)
Roelofs, J. M.B. (Radboud Universiteit Nijmegen)
Weerdesteyn, V. (Radboud Universiteit Nijmegen; Sint Maartenskliniek, Nijmegen)
van der Kooij, H. (TU Delft Biomechatronics & Human-Machine Control; University of Twente)
Schouten, A.C. (TU Delft Biomechatronics & Human-Machine Control; University of Twente)

2020

Changes in human balance control can objectively be assessed using system identification techniques in combination with support surface translations. However, large, expensive and complex motion platforms are required, which are not suitable for the clinic. A treadmill could be a simple alternative to apply support surface translations. In this paper we first validated the estimation of the joint stiffness of an inverted pendulum using system identification methods in combination with support surface translations, by comparison with the joint stiffness calculated using a linear regression method. Second, we used the system identification method to investigate the effect of horizontal ground reaction forces on the estimation of the ankle torque and the dynamics of the stabilizing mechanism of 12 healthy participants. Ankle torque and resulting frequency response functions, which describes the dynamics of the stabilizing mechanism, were calculated by both including and excluding horizontal ground reaction forces. Results showed that the joint stiffness of an inverted pendulum estimated using system identification is comparable to the joint stiffness estimated by a regression method. Secondly, within the induced body sway angles, the ankle torque and frequency response function of the joint dynamics calculated by both including and excluding horizontal ground reaction forces are similar. Therefore, the horizontal ground reaction forces play a minor role in calculating the ankle torque and frequency response function of the dynamics of the stabilizing mechanism and can thus be omitted.

Ankle torque
Stabilizing mechanism
Stiffness
System identification
Treadmill

http://resolver.tudelft.nl/uuid:3eae3c0c-313f-45a1-8885-69a1f083df4b

https://doi.org/10.1016/j.jbiomech.2020.109813

0021-9290

Journal of Biomechanics, 106

Institutional Repository

journal article

© 2020 I.M. Schut, J.H. Pasma, J. M.B. Roelofs, V. Weerdesteyn, H. van der Kooij, A.C. Schouten