Design and Analysis of a Novel Lightweight, Versatile Soft-rigid Robot

Soft robots are compliant to wrap large objects and adaptive to unstructured environments, while rigid robots can bend discretely at joints and pinch small objects easily. In this paper, we aim to create a novel robot that can behave like a rigid or soft robot adaptively, without additional stiffness-tunable mechanism. This approach makes the robot lightweight and practical. First, we present the fabricating process of the soft-rigid robot developed in the work. A steel flexure is especially optimized and embedded in the flexible body of the robot, which enhances the bending stiffness in the axial direction dramatically while keeping the body in other directions flexible and adaptive. Second, the kinematic model and analysis are developed to characterize the different configurations of the soft-rigid robot influenced by various parameters. Third, experiments are conducted to evaluate the performance of the flexible body and validate the accuracy of the kinematic model. Finally, a two-fingered gripper is built based on the soft-rigid robots, and grasping experiments are conducted to demonstrate how the soft-rigid robots could enhance the capability of the gripper in real-word.