Frictional and Prismatic Pin-Array Gripper for Universal Gripping and Stable Tool Manipulation
Cheonghwa Lee, Hyeongwon Kim, Midum Oh, Kisu Ok, Sung-Hoon Ahn
Abstract
Global trend in robotics has shifted towards deploying humanoid robots and mobile manipulators in industrial settings to automate repetitive and structured tasks traditionally performed by human workers. However, most tools and equipment are designed for human hands, and current grippers or end-effectors are highly specialized, limiting their ability to fully replace human handling of simple tools and tasks. This study proposes a novel frictional and prismatic pin-array gripper developed for universal gripping and tool manipulation. A pin-array structure of the gripper mimics the behavior of soft grippers while incorporating rigid components, enabling adaptability to various shapes and sizes. Each pin features semi-automatic actuation through a compression spring, supporting the underactuated mechanism. Most existing studies on grippers focus on simple pick-and-place tasks, whereas the proposed gripper extends functionality to practical tool usage. Enabled by the pin-array structure, it provides increased contact surface and support points, ensuring stable gripping and enhanced manipulation performance. In the evaluation, the pin-array gripper achieved a payload capacity of 2400 g, significantly outperforming the conventional RG2-FT gripper and the frictional flat gripper, which reached maximum capacities of 800 g and 400 g, respectively. It also exhibited higher grasping forces, measuring 1.17 times greater than the RG2-FT gripper and up to 23 times greater than the frictional flat gripper. For tool manipulation, the pin-array gripper exhibited significantly lower manipulation errors, with 21.67 and 6.59 times fewer errors than the RG2-FT and flat grippers, respectively, when handling the hammer, and 7.69 and 4.45 times fewer for the metal file. Additionally, qualitative demonstrations in universal gripping, omnidirectional gripping, and tool usage further validated the gripper’s performance in mobile manipulator tasks.