Design of a Fully Actuated 4-DOF Robotic Finger With Joint-Specific Hybrid Remote Actuation

2026-10-07

AI Summary

This study addresses the challenge of motion coupling and independent actuation in four-degree-of-freedom robotic finger joints by proposing a joint-specific hybrid remote actuation architecture. The design integrates rigid linkages with closed-loop tendon transmission mechanisms and incorporates rolling contact joints to maintain constant tendon length, thereby achieving complete mechanical decoupling between the proximal and distal interphalangeal joints along with independent control of each joint. Experimental results validate the effectiveness of this decoupling strategy, demonstrating peak fingertip forces of 21.28 N, 9.22 N, and 5.75 N across the respective joints. Furthermore, the proposed finger successfully grasps objects of diverse geometric shapes. This work provides a reliable mechanism design solution for fine manipulation tasks in dexterous robotic hands.

Abstract

This paper presents a fully actuated 4-DOF robotic finger using a joint-specific hybrid remote-actuation architecture. The metacarpophalangeal (MCP) joint is driven by two coordinated rigid-link transmission sets, whereas the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints are independently actuated by closed-loop wire transmissions incorporating circular rolling-contact joints (RCJs). A larger transmission radius is used at the PIP joint than at the DIP joint. The RCJ wire geometry maintains the total wire-loop length during joint rotation, and the DIP wire routing is designed so that PIP motion does not affect its differential actuation for a fixed MCP configuration. The distal wire transmission, MCP linkage, and fingertip kinematics are analytically modeled. In experiments, the transmission behavior was quantitatively evaluated from the ball-screw displacements measured using ArUco-marker tracking. MCP actuation produced measurable displacements of the PIP and DIP transmission units, whereas isolated PIP and DIP actuation with the MCP fixed supported the intended mechanical decoupling between the distal transmissions. The mean peak fingertip forces under isolated MCP, PIP, and DIP actuation were 21.28 N, 9.22 N, and 5.75 N, respectively. The resulting finger postures were also examined using objects of different geometries and sizes.

Problem

• Robotic finger
• Fully actuated
• Remote actuation
• Mechanical decoupling
• Degrees of freedom

Innovation

• Fully Actuated Robotic Finger
• Hybrid Remote Actuation
• Rolling-Contact Joints
• Mechanical Decoupling
• Closed-loop Wire Transmission