Document Type
Article
Publication Date
10-10-2023
Abstract
During behavior, the work done by actuators on the body can be resisted by the body's inertia, elastic forces, gravity, or viscosity. The dominant forces that resist actuation have major consequences on the control of that behavior. In the literature, features and actuation of locomotion, for example, have been successfully predicted by nondimensional numbers (e.g. Froude number and Reynolds number) that generally express the ratio between two of these forces (gravitational, inertial, elastic, and viscous). However, animals of different sizes or motions at different speeds may not share the same dominant forces within a behavior, making ratios of just two of these forces less useful. Thus, for a broad comparison of behavior across many orders of magnitude of limb length and cycle period, a dimensionless number that includes gravitational, inertial, elastic, and viscous forces is needed. This study proposes a nondimensional number that relates these four forces: the phase shift (Φ) between the displacement of the limb and the actuator force that moves it. Using allometric scaling laws, Φ for terrestrial walking is expressed as a function of the limb length and the cycle period at which the limb steps. Scale-dependent values of Φ are used to explain and predict the electromyographic (EMG) patterns employed by different animals as they walk.
Language
English
Publication Title
PNAS Nexus
Grant
2015317
Rights
© 2023 The Author(s). This is an Open Access work distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
G P Sutton, N S Szczecinski, R D Quinn, H J Chiel, Phase shift between joint rotation and actuation reflects dominant forces and predicts muscle activation patterns, PNAS Nexus, Volume 2, Issue 10, October 2023
Manuscript Version
Final Publisher Version