Friedman Jason, Flash Tamar
Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel.
Cortex. 2007 Apr;43(3):444-60. doi: 10.1016/s0010-9452(08)70469-6.
Object manipulation with the hand is a complex task. The task has redundancies at many levels, allowing many possibilities for the selection of grasp points, the orientation and posture of the hand, the forces to be applied at each fingertip and the impedance properties of the hand. Despite this inherent complexity, humans perform object manipulation nearly effortlessly. This article presents experimental findings of how humans grasp and manipulate objects, and examines the compatibility of grasps selected for specific tasks. This is accomplished by looking at the velocity transmission and force transmission ellipsoids, which represent the transmission ratios of the corresponding quantity from the joints to the object, as well as the stiffness ellipsoid which represents the directional stiffness of the grasp. These ellipsoids allow visualization of the grasp Jacobian and grasp stiffness matrices. The results show that the orientation of the ellipsoids can be related to salient task requirements.
用手进行物体操作是一项复杂的任务。该任务在许多层面上存在冗余，这使得在选择抓握点、手的方向和姿势、每个指尖施加的力以及手的阻抗特性方面有多种可能性。尽管存在这种固有的复杂性，但人类几乎毫不费力地就能进行物体操作。本文介绍了关于人类如何抓握和操作物体的实验结果，并研究了为特定任务选择的抓握方式的兼容性。这是通过观察速度传递椭球体和力传递椭球体来实现的，它们分别表示从关节到物体的相应量的传递比率，以及表示抓握方向刚度的刚度椭球体。这些椭球体能够直观显示抓握雅可比矩阵和抓握刚度矩阵。结果表明，椭球体的方向与突出的任务要求有关。
