3D printed, modularized rigid-flexible integrated soft finger actuators for anthropomorphic hands

Owing to the integrated muscular, ligamentous and skeletal structures and coupled degrees of freedom (DoFs), it is a long-term challenge in the field of robotics to design an anthropomorphic hand that mimics the biological structures and dexterous motions of human hands. In this paper, we present pneumatical, multi-material 3D-printed, modularized rigid-flexible integrated soft finger actuators (RFiSFAs) that can be directly assembled to an anthropomorphic hand. First, we introduce the mechanism of the RFiSFA with a pneumatic bellow chamber and a joint structure, and investigate the influence of the chamber material and the bellow number on the flexion angles and output forces performances of the RFiSFA. Next, we design and fabricate a 2-DoF flexion finger with two serial RFiSFAs and a 3-DoF thumb with two serial RFiSFAs and two parallel RFiSFAs. Then, we perform tests to characterize the motion and force performance of the fingers and thumb. Finally, we integrate and assemble an 11-DoF anthropomorphic hand with four flexion fingers and one thumb, and experimental results demonstrate the capability of the hand in grasping objects with different dimensions, shapes and textures.