RT Journal Article
SR Electronic
T1 Humans optimally anticipate and compensate for an uneven step during walking
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.12.01.407023
DO 10.1101/2020.12.01.407023
A1 Osman Darici
A1 Arthur D. Kuo
YR 2021
UL http://biorxiv.org/content/early/2021/01/05/2020.12.01.407023.abstract
AB The simple task of walking up a sidewalk curb is actually a dynamic prediction task. The curb is a disturbance that causes a loss of momentum, to be anticipated and compensated for. For example, the compensation might regain momentum and ensure undisturbed time of arrival. But without a selection criterion, there are infinite possible strategies. Here we show that humans compensate with an anticipatory pattern of forward speed adjustments, with a criterion of minimizing mechanical energy input. This is predicted by optimal control for a simple model of walking dynamics, with each leg’s push-off work as input. Optimization predicts a tri-phasic trajectory of speed (and thus momentum) adjustments, including an anticipatory, feedforward phase. In experiment, human subjects successfully regain time relative to undisturbed walking, with the predicted tri-phasic trajectory. They also scale the pattern with up- or down-steps, and inversely with average speed, as also predicted by model. Humans can reason about the dynamics of walking to plan anticipatory and economical control, even with a sidewalk curb in the way.Competing Interest StatementThe authors have declared no competing interest.