Citation

Matthis JS, Barton SL, Fajen BR. Proc. Natl. Acad. Sci. U. S. A. 2017; 114(32): E6720-E6729.

Affiliation

Cognitive Science Department, Rensselaer Polytechnic Institute, Troy, NY 12180.

Copyright

(Copyright © 2017, National Academy of Sciences)

DOI

10.1073/pnas.1611699114

PMID

28739912

Abstract

To walk efficiently over complex terrain, humans must use vision to tailor their gait to the upcoming ground surface without interfering with the exploitation of passive mechanical forces. We propose that walkers use visual information to initialize the mechanical state of the body before the beginning of each step so the resulting ballistic trajectory of the walker's center-of-mass will facilitate stepping on target footholds. Using a precision stepping task and synchronizing target visibility to the gait cycle, we empirically validated two predictions derived from this strategy: (1) Walkers must have information about upcoming footholds during the second half of the preceding step, and (2) foot placement is guided by information about the position of the target foothold relative to the preceding base of support. We conclude that active and passive modes of control work synergistically to allow walkers to negotiate complex terrain with efficiency, stability, and precision.

Language: en

Keywords

biomechanics; foot placement; human locomotion; inverted pendulum; visual control