Smooth enlargement of human standing sway by instability due to weak reaction floor and noise.
Smooth enlargement of human standing sway by instability due to weak reaction floor and noise.
复制标题
DOI：
10.1098/rsos.150570
复制
发表时间：
2016-01
影响因子：
3.5
通讯作者：
Tsuchiya K
中科院分区：
文献类型：
--
作者：
Funato T;Aoi S;Tomita N;Tsuchiya K
人类安静的站立伴随着身体的摇摆。众所周知，这种身体摇摆的幅度比从简单的噪音效应中预测的要大，摇摆特征会因神经障碍而改变。这种大的摆动被认为是由长时间无控制的非线性控制(间歇控制)引起的，并且这种类型的非线性控制系统已经被预测显示出分叉。稳定性依赖转换的存在使依赖于环境稳定性的动态反应成为可能，并可以解释某些神经疾病伴随的摇摆特征的变化。本研究分析了导致变迁的系统模型的特征，并讨论了人类地位是否反映了这种机制。在系统模型的数学分析中，(间歇控制类)积分控制的非线性控制表现出Hopf分叉。此外，从有噪声的系统模型的解析解可以看出，噪声对分岔点附近的摆动放大起到平滑作用。将此解与人体在不同稳定性地板上的站立摇摆进行了比较。通过对人的观测和模型预测的控制参数进行定量比较，表明摇摆的增大与模型分析所预测的一样。
Human quiet standing is accompanied by body sway. The amplitude of this body sway is known to be larger than would be predicted from simple noise effects, and sway characteristics are changed by neurological disorders. This large sway is thought to arise from nonlinear control with prolonged periods of no control (intermittent control), and a nonlinear control system of this kind has been predicted to exhibit bifurcation. The presence of stability-dependent transition enables dynamic reaction that depends on the stability of the environment, and can explain the change in sway characteristics that accompanies some neurological disorders. This research analyses the characteristics of a system model that induces transition, and discusses whether human standing reflects such a mechanism. In mathematical analysis of system models, (intermittent control-like) nonlinear control with integral control is shown to exhibit Hopf bifurcation. Moreover, from the analytical solution of the system model with noise, noise is shown to work to smooth the enlargement of sway around the bifurcation point. This solution is compared with measured human standing sway on floors with different stabilities. By quantitatively comparing the control parameters between human observation and model prediction, enlargement of sway is shown to appear as predicted by the model analysis.