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首页> 外文期刊>Journal of Biomechanics >Thresholds for step initiation induced by support-surface translation: a dynamic center-of-mass model provides much better prediction than a static model.
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Thresholds for step initiation induced by support-surface translation: a dynamic center-of-mass model provides much better prediction than a static model.

机译：由支撑表面平移引起的阶跃启动阈值：动态质量中心模型提供的预测比静态模型好得多。

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The need to initiate a step in order to recover balance could, in theory, be predicted by a static model based solely on displacement of the center of mass (COM) with respect to the base of support (BOS), or by a dynamic model based on the interaction between COM displacement and velocity. The purpose of this study was to determine whether the dynamic model provides better prediction than the static model regarding the need to step in response to moving-platform perturbation. The COM phase plane trajectories were determined for 10 healthy young adults for trials where the supporting platform was translated at three different acceleration levels in anterior and posterior directions. These trajectories were compared with the thresholds for step initiation predicted by the static and dynamic COM models. A single-link-plus-foot biomechanical model was employed to mathematically simulate termination of the COM movement, without stepping, using the measured platform acceleration as the input. An optimization routine was used to determine the stability boundaries in COM state space so as to establish the dynamic thresholds where a compensatory step must be initiated in order to recover balance. In the static model, the threshold for step initiation was reached if the COM was displaced beyond the BOS limits. The dynamic model showed substantially better accuracy than the static model in predicting the need to step in order to recover balance: 71% of all stepping responses predicted correctly by the dynamic model versus only 11% by the static model. These results support the proposition that the central nervous system must react to and control dynamic effects, i.e. COM velocity, as well as COM displacement in order to maintain stability with respect to the existing BOS without stepping.
机译：理论上，可以通过仅基于质心（COM）相对于支撑基础（BOS）的位移的静态模型或动态模型来预测需要采取步骤以恢复平衡的情况。基于COM位移和速度之间的相互作用。这项研究的目的是确定动态模型是否比静态模型提供更好的预测，以应对需要响应移动平台扰动的问题。确定了10位健康的年轻人的COM相平面轨迹，以进行试验，其中支撑平台在前后方向上以三种不同的加速度水平进行平移。将这些轨迹与静态和动态COM模型预测的步长起始阈值进行比较。使用测得的平台加速度作为输入，使用单连杆加脚生物力学模型来数学模拟COM运动的终止，而无需步进。使用优化例程来确定COM状态空间中的稳定性边界，以便建立动态阈值，在该阈值中必须启动补偿步骤才能恢复平衡。在静态模型中，如果COM位移超出BOS限制，则达到步长启动的阈值。动态模型在预测恢复平衡所需的脚步方面显示出比静态模型好得多的准确性：动态模型正确预测的所有步进响应中，有71％，而静态模型只有11％。这些结果支持以下主张：中枢神经系统必须对并控制动态影响，即COM速度以及COM位移，以相对于现有BOS保持稳定而不会步进。

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