Preliminary design of an anthropomorphic dexterous hand for a 2-years-old Humanoid: towards cognition

This paper presents first results in developing an anthropomorphic dextrous hand for a 2-years-old Humanoid. As this robot is aimed to be a physical platform for cognition, the number of degrees of freedom of the upper part of the body has been maximized. The robotic hand has 20 DoFs and 9 motors to accomplish optimal grasping and manipulation. Based on the manipulation tasks required in the project and on the human hand functional anatomy, we decided a mixed implementation of cable directed driven and under-actuated joints, locating most of the motors in the upper limb. The abduction/adduction of the fingers and the hollowing of the palm have been implemented and coupled together, driven by a single actuator. The first prototype has been developed; it includes the hand mechanism, the actuators and a proprioceptive sensory system for the joint positioning and the grasping force control. The sensor for cable tension and the design of the actuation units to be placed in the arm are described in detail.