Selective Variable Stiffness Flexible Manipulator for Dexterous In-Hand Manipulation

Abstract

Adaptive grasping and dexterous manipulation of random objects in unstructured environments have broad practical significance. Compared with traditional rigid manipulators, flexible manipulators possess better adaptability and safety, and thus are widely used in industrial, agricultural, and medical fields. However, since flexible manipulators are typically made of soft materials, their stability and dexterity are always limited. To make up for the deficiencies of existing flexible manipulators, this research proposes a variable stiffness flexible element driven by rope and evaluates its performance by finite element simulation and experimental methods. Based on the Fin Ray Effect, the flexible element is then assembled into a novel adaptive flexible manipulator, which can selectively regulate its local stiffness by driving a set of ropes. The flexible manipulator not only has multiple contact modes but also has good self-adaptability when interacting with the external environment. We also establish an integrated experimental platform and control system for in-hand manipulation and conduct quantitative in-hand manipulation experiments to obtain the mapping relationship between the driving input and the displacement of manipulated objects. Finally, we apply the flexible manipulator to daily charging tasks where the charging head can be rotated on demand. The manipulator has a broad application potential in real-world scenarios such as smart homes. In addition, the selective stiffness regulation methods proposed in this study provide a new approach to enhancing the multi-functionality of soft robotic structures.