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首页> 外文期刊>Journal of Biomechanics >Predicting dynamic postural instability using center of mass time-to-contact information.
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Predicting dynamic postural instability using center of mass time-to-contact information.

机译：使用质心接触时间信息预测动态姿势不稳定性。

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Our purpose was to determine whether spatiotemporal measures of center of mass motion relative to the base of support boundary could predict stepping strategies after upper-body postural perturbations in humans. We expected that inclusion of center of mass acceleration in such time-to-contact (TtC) calculations would give better predictions and more advanced warning of perturbation severity. TtC measures were compared with traditional postural variables, which do not consider support boundaries, and with an inverted pendulum model of dynamic stability developed by Hof et al. [2005. The condition for dynamic stability. Journal of Biomechanics 38, 1-8]. A pendulum was used to deliver sequentially increasing perturbations to 10 young adults, who were strapped to a wooden backboard that constrained motion to sagittal-plane rotation about the ankle joint. Subjects were instructed to resist the perturbations, stepping only if necessary to prevent a fall. Peak center of mass and center of pressure velocity and acceleration demonstrated linear increases with postural challenge. In contrast, boundary-relevant minimum TtC values decreased nonlinearly with postural challenge, enabling prediction of stepping responses using quadratic equations. When TtC calculations incorporated center of mass acceleration, the quadratic fits were better and gave more accurate predictions of the TtC values that would trigger stepping responses. In addition, TtC minima occurred earlier with acceleration inclusion, giving more advanced warning of perturbation severity. Our results were in agreement with TtC predictions based on Hof's model, and suggest that TtC may function as a control parameter, influencing the postural control system's decision to transition from a stationary base of support to a stepping strategy.
机译：我们的目的是确定相对于支撑边界基础的质心运动的时空量度是否可以预测人类上身姿势扰动后的步进策略。我们预计，在此类接触时间（TtC）计算中包括质心加速度中心将提供更好的预测和更严重的扰动严重性警告。将TtC量度与不考虑支撑边界的传统姿势变量以及Hof等人开发的动态稳定性倒立摆模型进行了比较。 [2005。动态稳定性的条件。生物力学学报38，1-8]。摆被用来向10位年轻的成年人连续施加不断增加的摄动，这些年轻人被绑在木制的背板上，从而限制了运动到围绕踝关节的矢状面旋转。指示受试者抵抗干扰，仅在必要时才采取措施以防止跌倒。质心峰值，压力中心的速度和加速度随姿势的挑战呈线性增加。相反，与姿势相关的挑战，与边界相关的最小TtC值非线性降低，从而可以使用二次方程式预测步进响应。当TtC计算并入质心加速度中心时，二次拟合会更好，并且会更精确地预测将触发步进响应的TtC值。此外，TtC极小值出现在较早的时间，并包含加速度，从而给出了更严重的摄动严重性警告。我们的结果与基于Hof模型的TtC预测相符，并表明TtC可能充当控制参数，影响姿势控制系统从固定支撑基础过渡到步进策略的决策。

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