Multi-fingered Robotic Hand with Shape Flexibility for Expanding the Feasible Range of In-hand Manipulation

In-hand manipulation with multi-fingered robotic hands is often limited by the restricted range of finger postures that can be achieved when handling objects. Expanding this range is crucial for enhancing the dexterity and versatility of robotic hands in various applications, such as assembly and precision tasks. One of the main limitations comes from the structural design of the fingers, which are typically composed of linked mechanisms comprising fixed-length links and rotational joints. To address this issue, this paper proposes the use of continuum robots for the fingers of multi-fingered hands. We detail the design of the robotic hand and its kinematic model using a constant curvature model, followed by simulations of finger reach and actual grasping experiments. The results of the grasping experiment show that the proposed robotic hand significantly expands the graspable range compared to conventional two-link robotic hands, due to its ability to greatly extend, retract, and bend.