An under-actuated robotic hand for multiple grasps

In this paper, an under-actuated robotic hand is designed for realizing several different grasps. Three special transmissions are developed to realize the compact joint connected motion, connected motion among fingers and adduction/abduction. These transmissions reduce the volume and weight of the hand while maintain functions necessary for realizing desired grasps. The developed robotic hand can choose three different opposed positions of the thumb to realize four different grasps. Experiments are conducted to confirm that the robotic hand moves fast and stably grasp objects.