A computational model for redundant human three-dimensional pointing movements: Integration of independent spatial and temporal motor plans simplifies movement dynamics
A computational model for redundant human three-dimensional pointing movements: Integration of independent spatial and temporal motor plans simplifies movement dynamics
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DOI：
10.1523/jneurosci.4334-06.2007
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发表时间：
2007-11-28
影响因子：
5.3
通讯作者：
Flash, Tamar
中科院分区：
文献类型：
--
作者：
Biess, Armin;Liebermann, Dario G.;Flash, Tamar
很少有计算模型能够解决无约束三维 (3D) 手臂运动的时空特征。对点对点运动期间的手部路径、速度曲线和手臂姿势进行的实证观察得出了手部路径和手臂姿势与运动速度无关的假设，这表明运动的几何和时间特性是解耦的。在这项研究中，我们提出了一个具有四个自由度的手臂 3D 运动的计算模型，该模型基于优化原理分别应用于控制的几何和时间级别的假设。几何属性（路径和姿态）是根据黎曼配置空间中动能度量的测地路径来定义的。因此，与任何其他非测地路径相比，可以用更少的肌肉力量来生成测地路径，因为所有与配置速度相关的扭矩的总和消失了。通过最小化沿所选末端执行器路径的平方加加速度，可以在任务空间中确定运动的时间属性（速度）。将两个规划级别集成到单个时空表示中简化了沿测地线路径的手臂动力学控制，并导致具有接近最小扭矩变化和最小动能峰值的运动。因此，黎曼几何的应用可以协调先前提出的用于描述手臂运动的计算模型。我们认为测地线是运动系统通过动态空间探索而产生的一个新兴属性。我们的数据验证了对关节轨迹、手部路径、最终姿势、速度曲线和驱动扭矩的预测。
Few computational models have addressed the spatiotemporal features of unconstrained three-dimensional (3D) arm motion. Empirical observations made on hand paths, speed profiles, and arm postures during point-to-point movements led to the assumption that hand path and arm posture are independent of movement speed, suggesting that the geometric and temporal properties of movements are decoupled. In this study, we present a computational model of 3D movements for an arm with four degrees of freedom based on the assumption that optimization principles are separately applied at the geometric and temporal levels of control. Geometric properties ( path and posture) are defined in terms of geodesic paths with respect to the kinetic energy metric in the Riemannian configuration space. Accordingly, a geodesic path can be generated with less muscular effort than on any other, nongeodesic path, because the sum of all configuration-speed- dependent torques vanishes. The temporal properties of the movement ( speed) are determined in task space by minimizing the squared jerk along the selected end- effector path. The integration of both planning levels into a single spatiotemporal representation simplifies the control of arm dynamics along geodesic paths and results in movements with near minimal torque change and minimal peak value of kinetic energy. Thus, the application of Riemannian geometry allows for a reconciliation of computational models previously proposed for the description of arm movements. We suggest that geodesics are an emergent property of the motor system through the exploration of dynamical space. Our data validated the predictions for joint trajectories, hand paths, final postures, speed profiles, and driving torques.