Department of Mechanical Engineering, KAIST, Daejeon, Republic of Korea.
J Biomech. 2012 May 11;45(8):1379-86. doi: 10.1016/j.jbiomech.2012.03.001. Epub 2012 Mar 23.
In this study we examined whether the selection of postural feedback gain and its scaling is dependent on perturbation type. We compare forward pushes applied to the back of a standing subject to previous work on responses to support translation. As was done in the previous work, we quantified the subject's response in terms of perturbation-dependent feedback gains. Seven healthy young subjects (25±3 yr) experienced five different magnitudes of forward push applied by a 1.25 m-long pendulum falling from the height of 1.4m toward the center of mass of the subject's torso. The loads on the pendulum ranged from 2 to 10 kg. Impulsive force, ground reaction forces and joint kinematics were measured, and joint torques were calculated from inverse dynamics. A full-state feedback control model was used to quantify the empirical data, and the feedback gains that minimized the fitting error between the data and model simulation were identified. As in previously published feedback gains for support translation trials, gradual gain scaling with push perturbation magnitude was consistently observed, but a different feedback gain set was obtained. The results imply that the nervous system may be aware of body dynamics being subjected to various perturbation types and may select perturbation-dependent postural feedback gains that satisfy postural stability and feasible joint torque constraints.
在这项研究中，我们研究了姿势反馈增益的选择及其缩放是否取决于扰动类型。我们将比较施加在站立受试者背部的向前推动与之前关于对支撑平移响应的研究。就像之前的工作一样，我们根据扰动相关的反馈增益来量化受试者的响应。7 名健康的年轻受试者（25±3 岁）经历了从 1.4m 高度下降的 1.25m 长摆锤施加的五种不同大小的向前推动。摆锤上的负载范围从 2 到 10 公斤。测量了冲击力、地面反作用力和关节运动学，并从逆动力学计算了关节扭矩。使用全状态反馈控制模型来量化经验数据，并确定了使数据和模型模拟之间的拟合误差最小化的反馈增益。与之前发布的用于支撑平移试验的反馈增益一样，逐渐的增益与推动扰动幅度的比例缩放得到了一致的观察，但得到了不同的反馈增益集。结果表明，神经系统可能意识到身体动力学受到各种扰动类型的影响，并可能选择满足姿势稳定性和可行关节扭矩约束的与扰动相关的姿势反馈增益。
