Design and Optimization of a Tensioner-Driven Compliant Pulley Mechanism for Supermicrosurgical Robot End-Effectors
Min Chul Kim, Young Min Lee, Yong Seok Ihn
AI summary
Problem
Conventional cable-driven surgical robot end-effectors suffer from unpredictable tension fluctuations and cable elongation, which degrade the sub-millimeter precision required for supermicrosurgery.
Approach
The authors designed a tensioner-driven pulley mechanism that uses spring displacement to dynamically maintain optimal wire tension, supported by a nonlinear kinematic model and MATLAB-based parameter optimization.
Key results
- Nonlinear kinematic and static equilibrium model for spring-pulley-wire interaction
- MATLAB optimization routine identifying optimal neutral point for static symmetry
- Stable grasping force maintained across ±40° rotation range
- Target torque of 5 mNm achieved with a defined hardware Safe Zone
Why it matters
Provides a robust hardware foundation for next-generation supermicrosurgical robots requiring sub-millimeter precision and reliable needle and suture manipulation.
Abstract
Supermicrosurgery requires exceptionally high- precision 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 sys- tems, it is critical to ensure the stable grasping and delicate ma- nipulation of ultra-fine needles and sutures under varying surgi- cal 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 tensioner- driven pulley displacement, allowing the system to maintain optimal tension dynamically.We present a comprehensive math- ematical framework that includes a non-linear kinematic model and static equilibrium equations to describe the interaction between 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 by the rotation of the motor shaft.Our results demonstrate that the mechanism ensures a stable grasping force even at significant angular displacements, with a specific rotation range of ±40◦ optimized for surgical needle manipulation. This compliant pulley system effectively resolves geometric complexities and ensures driving symmetry, providing a robust hardware solution for next-generation supermicrosurgical robots. The integration of this mechanism promises to enhance the control precision and reliability of robotic end-effectors in delicate surgical environments.