Blue Hand: A Novel Type of Soft Anthropomorphic Hand Based on Pneumatic Series-Parallel Mechanism

Hand dexterity is tremendously valuable to robots for task-dependent manipulation and interacting with the world. In this work, we present a novel soft pneumatic dexterous hand, which demonstrates highly dexterous and versatile anthropomorphic properties. Inspired by human hand, the proposed hand possesses 21 degrees of freedoms (DOFs), is implemented in anthropomorphic fingers, soft parallel palm and the ability to spread the fingers with a modular design. The anthropomorphic fingers are designed in accordance with the joint distribution of the human fingers. By using a layered design, each independent actuator is divided into an actuating layer and a contact layer, which allows the grasping mode and the contact mode to be adjusted in real-time. To streamline the creation of the palm and improve the dexterity of the hand, the soft parallel palm is actuated by bellow actuators, designed by using the characteristics of a compact structure and stable movement of the parallel mechanism. Additionally, the bellow actuators are also used to realize the ability to spread the fingers and assist the carpometacarpal (CMC) joint bending of the thumb through the passive deformation of the flexible joint. Through series of experiments, we evaluate the hand by demonstrating its ability to achieve the highest possible score in the Kapandji test for thumb dexterity, to realize all 33 grasp types of the comprehensive GRASP taxonomy, and to interact with humans in the real world.