Three-Fingered Eight-DOF Hand That Exerts 100-N Grasping Force With Force-Magnification Drive

This paper presents a three-fingered, eight-DOF hand, 100 N Hand II, which can exert a grasping force of 100 N. A force-magnification drive, which can maintain a large grasping force without energy consumption, allows the hand to exert such large grasping force, and a high-speed driving mechanism enables all joints to perform high-speed motions of over 400°/s. In our previous prototype (100 N Hand I), a screw and nut mechanism was used to implement force magnification. The linear motion of this mechanism was translated to rotational joint motion via a linkage mechanism, producing a relatively small motion range for each joint and with large palm dimensions. 100 N Hand II employs a worm gear instead of a screw and nut mechanism, so it can magnify the torque at an arbitrary joint angle. This improved force-magnification drive increases the motion range of each joint and reduces the palm size. The force and speed are confirmed experimentally.