Design and Optimization of a Tensioner-Driven Compliant Pulley Mechanism for Supermicrosurgical Robot End-Effectors

Abstract

Supermicrosurgery requires exceptionally highprecision manipulation to perform anastomosis of microscopic vessels and nerves, often involving diameters between 0.3 mm and 0.8 mm. To achieve successful outcomes with robotic systems, it is critical to ensure the stable grasping and delicate manipulation of ultra-fine needles and sutures under varying surgical conditions.This paper proposes a spring-based flexible pulley mechanism designed specifically to overcome the fundamental limitations of conventional cable-driven systems, most notably the unpredictable tension fluctuations. Instead of traditional fixed pulleys, the proposed mechanism introduces a tensionerdriven pulley displacement, allowing the system to maintain optimal tension dynamically.We present a comprehensive mathematical framework that includes a non-linear kinematic modeland static equilibrium equations to describe the interactionbetween spring compression and wire tension. To maximize manipulation performance, we performed optimization of the design parameters using MATLAB simulations, focusing on the guaranteed grasping force and the workspace limits defined bythe rotation of the motor shaft.Our results demonstrate that themechanism ensures a stable grasping force even at significantangular displacements, with a specific rotation range of ±40◦optimized for surgical needle manipulation. This compliantpulley system effectively resolves geometric complexities andensures driving symmetry, providing a robu