Evaluation of a model that determines the stability limits of dynamic balance
Evaluation of a model that determines the stability limits of dynamic balance
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DOI：
10.1016/s0966-6362(98)00037-x
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发表时间：
1999-03-01
期刊：
影响因子：
2.4
通讯作者：
Lee, WA
中科院分区：
文献类型：
--
作者：
Patton, JL;Pai, YC;Lee, WA
最近的平衡控制模型揭示了两种描述质心 (CM) 动力学稳定性极限的边界：扭矩边界和状态边界。本研究的目的是确定这些边界是否正确地表征了经验数据。我们分析了 10 名受试者的 2367 项试验，这些受试者在自愿拉动把手后恢复了平衡。我们假设，如果模型预测有效，则两种类型的边界都应包含经验轨迹。我们还假设每个轨迹到扭矩边界（扭矩安全裕度）的最近距离将与压力中心（COP）安全裕度相关，定义为 COP 到脚边缘的最近距离。结果支持了模型导出边界的准确性，其中扭矩边界涵盖了 100% 的试验，状态边界涵盖了 99.8% 的试验。此外，扭矩安全裕度与 COP 安全裕度高度相关，支持使用 COP 安全裕度来估计保持平衡的动态任务中的相对稳定性。轨迹的分布还表明，以安全裕度为导向的控制策略可能是中枢神经系统努力优化运动假设的有力替代方案。讨论了不同安全裕度之间的区别。 (C) 1999 Elsevier Science B.V. 保留所有权利。
A recent model of balance control has revealed two types of boundaries describing stability limits for center of mass (CM) dynamics: torque boundaries and state boundaries. The purpose of this study was to determine if these boundaries correctly characterize empirical data. We analyzed 2367 trials from 10 subjects who recovered their balance after they voluntarily pulled on a handle. We hypothesized that if model predictions were valid, both types of boundaries should encompass the empirical trajectories. We also hypothesized that each trajectory's nearest distance to the torque boundaries (the torque safety margin) would be correlated with the center of pressure (COP) safety margin, defined as the COP's nearest distance to the edge of the feet. The results supported the accuracy of the model-derived boundaries, with torque boundaries encompassing 100% and state boundaries encompassing 99.8% of the trials. Moreover, torque safety margins were highly correlated with COP safety margins, supporting the use of COP safety margins for estimating relative stability in dynamic tasks where balance is maintained. The distributions of the trajectories also suggested that a safety margin-oriented control strategy might be a robust alternative to the hypothesis that the central nervous system strives to optimize motion. The distinctions among different safety margins are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.