Human stick balancing: Tuning Levy flights to improve balance control
Human stick balancing: Tuning Levy flights to improve balance control
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DOI：
10.1063/1.1785453
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发表时间：
2004-09-01
期刊：
影响因子：
2.9
通讯作者：
Milton, JG
中科院分区：
文献类型：
--
作者：
Cabrera, JL;Milton, JG
状态相关或参数噪声是指尖杆平衡神经控制机制的重要组成部分。三维高速运动分析表明，操纵杆平衡过程中指尖的控制运动可以用 Levy 飞行来描述。 Levy 指数 alpha 约为 0.9；接近随机搜索最佳值的值。随着技能的提高，阿尔法指数不会改变。然而，利维分布的尾部变得更宽。这些观察结果表明，利维飞行被神经和肌肉骨骼系统的特性所截断；截断随着技能水平的提高而减少。对棍尖和指尖位置之间互相关性的测量表明，闭环反馈的作用随着技能的提高而变化。此外，对操纵杆平衡的神经延迟的估计表明，对于给定的操纵杆长度，延迟随着技能水平的增加而增加。有人提出，操纵杆平衡的神经控制涉及一种机制，其中有意识产生的纠正运动的短暂间隔与无预测控制的较长间隔交替。通过学习，Levy 飞行的截断对于平衡控制变得更好优化，因此连续有意识修正之间的时间增加。这些观察结果提供了第一个证据，表明利维飞行的变化可能对神经系统具有功能意义。这项工作对于控制平衡问题具有重要意义，从老年人跌倒到两足机器人和抗震建筑的设计。 (C) 2004 年美国物理研究所。
State-dependent, or parametric, noise is an essential component of the neural control mechanism for stick balancing at the fingertip. High-speed motion analysis in three dimensions demonstrates that the controlling movements made by the fingertip during stick balancing can be described by a Levy flight. The Levy index, alpha, is approximately 0.9; a value close to optimal for a random search. With increased skill, the index alpha does not change. However, the tails of the Levy distribution become broader. These observations suggest a Levy flight that is truncated by the properties of the nervous and musculoskeletal system; the truncation decreasing as skill level increases. Measurements of the cross-correlation between the position of the tip of the stick and the fingertip demonstrate that the role of closed-loop feedback changes with increased skill. Moreover, estimation of the neural latencies for stick balancing show that for a given stick length, the latency increases with skill level. It is suggested that the neural control for stick balancing involves a mechanism in which brief intervals of consciously generated, corrective movements alternate with longer intervals of prediction-free control. With learning the truncation of the Levy flight becomes better optimized for balance control and hence the time between successive conscious corrections increases. These observations provide the first evidence that changes in a Levy flight may have functional significance for the nervous system. This work has implications for the control of balancing problems ranging from falling in the elderly to the design of two-legged robots and earthquake proof buildings. (C) 2004 American Institute of Physics.