Hybrid Visual Servoing for Robotic Assistance in ENT Microsurgery: A Case Study on Middle Ear Access *

This paper introduces a robotic assistance system for minimally invasive middle ear surgery, focusing on precise access to the tympanic membrane. The system combines a 7-degree-of-freedom robotic arm with a hybrid visual servoing framework that integrates position-based and image-based control strategies. Dual visual feedback from a color camera and an endoscope enables robust 6-DoF pose estimation and sub-millimetric tool guidance. A model-based tracker and blob detection ensure accurate alignment and targeting, while a Quadratic Programming controller enforces safety constraints such as maintaining the field of view. The approach is validated through simulations and real-world experiments, demonstrating high accuracy, robustness to anatomical variability, and suitability for clinical integration. This work advances robotic microsurgery by providing a closed-loop, constraint-aware control architecture tailored for otologic procedures.