Department of Computer Science, The University of Texas at Austin, Austin, TX, USA.
Sci Rep. 2021 Oct 11;11(1):20081. doi: 10.1038/s41598-021-99423-5.
Humans have elegant bodies that allow gymnastics, piano playing, and tool use, but understanding how they do this in detail is difficult because their musculoskeletal systems are extraordinarily complicated. Nonetheless, common movements like walking and reaching can be stereotypical, and a very large number of studies have shown their energetic cost to be a major factor. In contrast, one might think that general movements are very individuated and intractable, but our previous study has shown that in an arbitrary set of whole-body movements used to trace large-scale closed curves, near-identical posture sequences were chosen across different subjects, both in the average trajectories of the body's limbs and in the variance within trajectories. The commonalities in that result motivate explanations for its generality. One explanation could be that humans also choose trajectories that are economical in cost. To test this hypothesis, we situate the tracing data within a forty eight degree of freedom human dynamic model that allows the computation of movement cost. Using the model to compare movement cost data from nominal tracings against various perturbed tracings shows that the latter are more energetically expensive, inferring that the original traces were chosen on the basis of minimum cost.
人类拥有优雅的身体，使他们能够进行体操、钢琴演奏和使用工具，但要详细了解他们是如何做到这一点的却很困难，因为他们的骨骼肌肉系统非常复杂。尽管如此，像行走和伸手这样常见的动作可能是刻板的，而且大量的研究表明它们的能量成本是一个主要因素。相比之下，人们可能认为一般的动作非常个性化和难以捉摸，但我们之前的研究表明，在一组用于追踪大规模封闭曲线的任意全身运动中，不同受试者选择了几乎相同的姿势序列，无论是在身体四肢的平均轨迹还是在轨迹内的方差中。这一结果的共性为其普遍性提供了解释。一种解释可能是，人类也选择在成本上经济的轨迹。为了验证这一假设，我们将追踪数据置于一个具有四十八个自由度的人体动力学模型中，该模型允许计算运动成本。使用该模型比较标称轨迹和各种受扰轨迹的运动成本数据表明，后者的能量成本更高，这表明原始轨迹是基于最低成本选择的。
