Multi-directional Ankle Impedance During Standing Postures
Multi-directional Ankle Impedance During Standing Postures
复制标题
站立姿势时的多向踝关节阻抗
DOI：
10.1109/tnsre.2020.3018650
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发表时间：
2020
影响因子：
4.9
通讯作者：
Rastgaar, Mo
中科院分区：
文献类型：
--
作者：
Ribeiro, Guilherme A.;Knop, Lauren N.;Rastgaar, Mo
在本研究中，我们估计了站立时两个自由度（DOF）踝关节的多向机械阻抗，并确定了不同姿势下踝关节角度和踝关节扭矩对关节刚度、阻尼和惯量的影响。15名受试者站在一个振动的仪器平台上，以四种静止的姿势站立，同时在矢状面和额状面运动中受到脉冲序列的扰动。选择四个静止的姿势来模拟步态周期的站立阶段：包括加载反应时脚跟撞击后、站立中期、站立中期和站立结束阶段脚跟离地之前。一般来说，随着足部COP向前移动，踝关节的刚度和阻尼在各个方向上都增加，跖屈曲时产生更多的扭矩。有趣的是，站立时踝关节的多向阻抗显示出与无负载情况相似的形状和主要倾斜轴。然而，当踝关节不受体重负荷时，阻抗振幅有显著差异。最后，站立时的刚度与以往研究估计的动态步行站立时踝关节时变刚度的幅度范围相似。这些结果对设计新的、体力强度较低的生物力学实验具有启示意义，这些实验针对的是那些患有神经肌肉疾病或其他身体缺陷、无法完成标准步态测试的人。
In this study, we estimated the multi-directional ankle mechanical impedance in two degrees-of-freedom (DOF) during standing, and determined how the stiffness, damping, and inertia vary with ankle angle and ankle torque at different postures. Fifteen subjects stood on a vibrating instrumented platform in four stationary postures, while subjected to pulse train perturbations in both the sagittal and frontal planes of motion. The four stationary postures were selected to resemble stages within the stance phase of the gait cycle: including post-heel-strike during the loading response, mid-stance, post-mid-stance, and just before the heel rises from the ground in terminal-stance phase. In general, the ankle stiffness and damping increased in all directions as the foot COP moved forward, and more torque is generated in plantarflexion. Interestingly, the multi-directional ankle impedance during standing showed a similar shape and major tilt axes to the results of non-loaded scenarios. However, there were notable differences in the impedance amplitude when the ankle was not under bodyweight loading. Last, the stiffness during standing had similar amplitudes ranges to the time-varying ankle stiffness during the stance phase of dynamic walking estimated in previous studies. These results have implications on the design of new, less physically intense, biomechanics experiments aimed at people with neuromuscular disorders or other physical impairments who cannot complete a standard gait test.