抓持接触力的空间分解及计算

机器人灵巧手抓持和操作物体所需要的力来自手指与物体之间的接触力。本文在静力学范围内研究对于给定的抓持和操作任务，如何简便、有效和最优地确定抓持接触力。首先将接触力空间分解为４个互补子空间，用于空间的维数判别可控与不可控接触内力。继而提出一种确定各子空间基的简单方法，将接触力分解为４个分量，并将其写成物理所受外力和手指关节力矩之间的显函数，达到减少最优变量和保证优化结果可实现的目的。文中用两个数值算例显示了方法的简便和有效。

Calculation of Contact Forces in Grasping by Space Decomposition

Robotic hands grasp and manipulate objects through the contact forces between the fingers and the objects. The determination of contact forces in grasping is discussed in this paper. To systematically investigate the characteristics of different grasps, the vector space of contact forces is decomposed into four subspaces and their basis is found by an efficient computational method. The vector of contact forces is then formulated into four components: active and passive grasping forces, controllable and uncontrollable internal forces. The dimen sions of the subspaces identify uncontrollable internal forces. The contact force is further expressed into an ex- plicit function of the external wrench and the joint torques. The resulting formulation simplifies the computation in the optimization of contact forces and makes the optimal variables controllable. Two numerical cases are given to show the simplicity and validity of the method.