Stability radius as a method for comparing the dynamics of neuromechanical systems.
Stability radius as a method for comparing the dynamics of neuromechanical systems.
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DOI：
10.1109/tnsre.2013.2264920
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发表时间：
2013-09
期刊：
影响因子：
--
通讯作者：
Ting LH
中科院分区：
文献类型：
--
作者：
Bingham JT;Ting LH
强健的运动行为来自非线性的、具有延迟的、包含冗余神经和生物力学成分的神经机械相互作用。例如，在站立平衡中，受试者的肌肉活动（神经控制）随着站立宽度（生物力学）在响应于横向扰动时增加而减小，然而质心运动（行为）几乎相同，而不管站立宽度。我们提出了稳定半径，这是一种来自鲁棒控制理论的技术，以克服经典稳定性分析工具的局限性，例如增益裕度，这些工具不足以预测生物力学（植物）和神经控制（控制器）的并发变化如何影响系统行为。我们首先提出的理论，然后应用到一个神经力学模型的额面站立平衡与延迟反馈。我们表明，稳定半径可以量化系统行为对参数变化的敏感性差异，并预测，缩小立场宽度增加系统的鲁棒性。我们进一步证明，选择具有相同稳定半径的站立宽度（生物力学）和反馈增益（神经控制）的组合在模拟中产生类似的质心行为。因此，稳定半径可以提供一个有用的工具，了解运动中的神经机械相互作用，并可以帮助设计的设备和治疗，以改善运动功能。
Robust motor behaviors emerge from neuromechanical interactions that are nonlinear, have delays, and contain redundant neural and biomechanical components. For example, in standing balance a subject’s muscle activity (neural control) decreases as stance width (biomechanics) increases when responding to a lateral perturbation, yet the center-of-mass motion (behavior) is nearly identical regardless of stance width. We present stability radius, a technique from robust control theory, to overcome the limitations of classical stability analysis tools, such as gain margin, which are insufficient for predicting how concurrent changes in both biomechanics (plant) and neural control (controller) affect system behavior. We first present the theory and then an application to a neuromechanical model of frontal-plane standing balance with delayed feedback. We show that stability radius can quantify differences in the sensitivity of system behavior to parameter changes, and predict that narrowing stance width increases system robustness. We further demonstrate that selecting combinations of stance width (biomechanics) and feedback gains (neural control) that have the same stability radius produce similar center-of-mass behavior in simulation. Therefore, stability radius may provide a useful tool for understanding neuromechanical interactions in movement and could aid in the design of devices and therapies for improving motor function.