Abstract
Robots have been expected to do services instead of human. Especially, Manipuration of tools with a multifingered robot hand is very important, because the hand has the grasping capability of a large variety of objects. In this paper, we deal with "manipulating scissors" by a maltifingered robot hand. First, we derive the force relationship between the contact forces and the object force, where the hyperstatic forces are included. Second, we propose a decomposition of the contact force where the hyperstatic forces are taken into account.