Under-actuated humanoid robot hand with changeable grasping force

Abstract

Most conventional dexterous hands have too many DOFs, large drive systems and complicated controls so they can not be installed in a humanoid robot arm. This paper introduces the mechanical characteristics of an underactuated humanoid robot hand (TH1 hand) with changeable grasping force. The TH1 hand has a mechanical finger with changeable grasping force for a more stable grip. The TH1 thumb is an underactuated mechanical finger which has more DOFs with fewer drivers. The driving motors and control circuits are embedded inside the hand. The TH1 appearance and size are similar to a human hand. The hand is of lighter weight, has fewer DOFs, and can be easily controlled. Tests showed that the TH1 hand mounted in a humanoid robot can move with many anthropopathic actions such as extending, making a fist, and stably grasping objects of different sizes and shapes with variable force levels. The changeable grasping force finger mechanism and the underactuated thumb mechanism can also be used in other force transmission systems such as gear transmissions.