Anthropomorphic Soft Pneumatic Fingers Towards Full Dexterity of Human Hand

Abstract

Human fingers are highly dexterous due to the combination of multiple joints and degrees of freedom (DoFs). With the rise of soft material robots, many gripper prototypes have utilized soft robot technology. Nonetheless, it is still challenging to build a soft finger with a similar dexterity to human hand. Owing to the soft pneumatic actuator (SPA) fabrication flexibility, we have proposed a multiple DoFs soft pneumatic fingers design scheme that can mimic the motion patterns of human hand. Unlike the most SPA fingers where the motion patterns are fixed and limited, here our soft fingers can function like the human finger movements to a greater extent. The design is composed of three parts: (i) a SPA with two independent chambers as the main part of finger; (ii) a constraint layer made of unstretchable fabric which simulates tendon; (iii) a fiber-reinforced three-channel fluidic elastomer actuator (FEA). The abundance in DoFs expands the range of motions of the fingers and enables them to reach where human fingers can go. By controlling the internal pressure of the actuator, a variety of human finger motion patterns are achieved. Since each chamber's pressure can be individually controlled, the dexterous position control of the finger has been made possible. Fabrication process of the soft pneumatic fingers is presented, followed by the characterizations to provide a better understanding of their behaviors. In the last part of the article, a robotic hand composed of five fingers is fabricated for demonstration.