Development of a Miniaturized 6-DoF Surgical Instrument with a 4-Mm Elbow and 3-Mm Wrist for Transoral Robotic Surgery

Abstract

Current platforms for Transoral Robotic Surgery (TORS) are suboptimal for confined oropharyngeal workspaces, particularly in pediatric applications. To address this, we present the design and characterization of a novel cable-driven robotic instrument providing 6 degrees-of-freedom (DoF)—shaft roll, elbow pitch/yaw, wrist pitch/yaw, and grip—for dexterous manipulation. The system integrates a miniaturized 4-mm proximal elbow with a previously developed 3-mm distal wrist. This architecture is enabled by a novel “sandwich” link architecture that facilitates high-density cable routing through the joint’s center plane, providing a compact, rigid alternative to traditional pin-jointed designs. Experimental validation identified significant kinematic coupling between in-plane joint pairs. An empirical real-time compensation strategy reduced this coupling rate by 82.9% for pitch and 80.8% for yaw. Workspace analysis confirmed the proximal elbow enables high distal dexterity at regions critical for complex surgical tasks. Integration with a Franka Research 3 manipulator enabled fully coordinated macro-micro teleoperation, providing a pilot demonstration for TORS workflows. This represents the first demonstration of a 4-mm elbow-3mm wrist mechanism for TORS, providing the hardware foundation necessary for future evaluation of dexterity-intensive tasks, including suturing and dissection.