Wang Yang, Srinivasan Manoj
Mechanical and Aerospace Engineering, The Ohio State University, Columbus, OH 43210, USA.
Mechanical and Aerospace Engineering, The Ohio State University, Columbus, OH 43210, USA
Biol Lett. 2014 Sep;10(9). doi: 10.1098/rsbl.2014.0405.
During human walking, perturbations to the upper body can be partly corrected by placing the foot appropriately on the next step. Here, we infer aspects of such foot placement dynamics using step-to-step variability over hundreds of steps of steady-state walking data. In particular, we infer dependence of the 'next' foot position on upper body state at different phases during the 'current' step. We show that a linear function of the hip position and velocity state (approximating the body center of mass state) during mid-stance explains over 80% of the next lateral foot position variance, consistent with (but not proving) lateral stabilization using foot placement. This linear function implies that a rightward pelvic deviation during a left stance results in a larger step width and smaller step length than average on the next foot placement. The absolute position on the treadmill does not add significant information about the next foot relative to current stance foot over that already available in the pelvis position and velocity. Such walking dynamics inference with steady-state data may allow diagnostics of stability and inform biomimetic exoskeleton or robot design.
在人类行走过程中，对上半身的扰动可以通过在下一步中适当地放置脚来部分纠正。在这里，我们利用数百步稳态行走数据中的步间变异性来推断这种脚部放置动态的各个方面。特别是，我们推断“下一步”脚部位置在“当前”步的不同阶段对上半身状态的依赖性。我们表明，站立中期臀部位置和速度状态（近似身体质心状态）的线性函数解释了下一个侧向脚部位置方差的80%以上，这与使用脚部放置进行侧向稳定（但未证明）一致。这种线性函数意味着，在左站立期间骨盆向右偏移会导致下一次脚部放置时步宽比平均步宽大，步长比平均步长短。相对于骨盆位置和速度中已有的信息，跑步机上的绝对位置并没有增加关于相对于当前站立脚的下一个脚部的重要信息。利用稳态数据进行这种行走动态推断可能有助于稳定性诊断，并为仿生外骨骼或机器人设计提供信息。
