A Soft Finger Resistant to Lateral Forces through Endoskeleton Embedding

Soft robotic hands have attracted widespread attention due to their unique compliance, but the overly soft material makes it difficult for them to maintain their own shape, which contradicts the original intention of soft hands to mimic the human hand. This paper introduces a soft finger embedded in endoskeleton (SFEE) that enhances its resistance to lateral forces without compromising its flexion-extension capabilities. Inspired by the interphalangeal joints of human fingers, the endoskeleton adopts a hinge-like connection. The endoskeleton consists of multiple interconnected units, which are articulated and embedded within the chamber of the soft finger. This paper describes the design, fabrication process, and preliminary performance testing of SFEE. The necessity of the soft finger to resist the lateral force is demonstrated by finite element simulation and the grasping ability of SFEE is demonstrated using a three fingers gripper. Due to the purely passive bending of the endoskeleton and its small size, it can be applied to most soft actuators with cavities to reproduce the characteristics of human hands.