Design and Fabrication of a Variable Stiffness Soft Pneumatic Humanoid Finger Actuator

Abstract

Soft actuators are popular used in bionic robotic hands and grippers due to its flexibility and compliance. However, most of them can't achieve true finger-like motion and have low stiffness. Inspired by the human fingers, this paper introduce a new design of three-joint variable stiffness pneumatic soft finger actuator, which imitate the shape, size, motion pattern and rigid-flexible coupled characteristic of human fingers. The soft finger is designed into four sections and three joints. The metacarpophalangeal joint is driven independently and the other two interphalangeal joints are driven associated. The soft finger actuator uses Low-melting point alloys (LMPA) as a stiffening layer to achieve a controllable and variable functions of stiffness. Motion and stiffening performance of the finger actuator is tested. The result shows that the combination pattern of soft and rigid has an improvement in performance of soft finger actuators.