Center for Perceptual Systems, University of Texas at Austin, Austin, TX 78712;
Cognitive Science Department, Rensselaer Polytechnic Institute, Troy, NY 12180.
Proc Natl Acad Sci U S A. 2017 Aug 8;114(32):E6720-E6729. doi: 10.1073/pnas.1611699114. Epub 2017 Jul 24.
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.
为了在复杂地形上高效行走，人类必须利用视觉根据即将出现的地面状况调整步态，同时又不干扰对被动机械力的利用。我们提出，步行者在每一步开始之前，使用视觉信息来初始化身体的机械状态，以便步行者质心的弹道轨迹将有利于踏在目标立足点上。通过使用精确的踏步行走任务，并使目标可见性与步态周期同步，我们从该策略中验证了两个预测：（1）步行者必须在前一步的后半段期间获得关于即将到来的立足点的信息；（2）脚的放置受到目标立足点相对于前支撑基础的位置的信息的指导。我们的结论是，主动和被动控制模式协同工作，使步行者能够高效、稳定和精确地穿越复杂地形。
