Safe Path following for Middle Ear Surgery

TL;DR

This paper presents a hierarchical path-following controller for surgical robotics in middle ear surgery, capable of handling constrained motions like RCM and UCM, validated through simulation and experiments achieving sub-100 micrometer accuracy.

Contribution

It introduces a novel hierarchical control method for constrained path following in surgical robotics, specifically tailored for middle ear procedures.

Findings

Validated on simulator and experimental platform

Achieved accuracy below 100 micrometers

Demonstrated effective handling of RCM and UCM constraints

Abstract

This article formulates a generic representation of a path-following controller operating under contained motion, which was developed in the context of surgical robotics. It reports two types of constrained motion: i) Bilateral Constrained Motion, also called Remote Center Motion (RCM), and ii) Unilaterally Constrained Motion (UCM). In the first case, the incision hole has almost the same diameter as the robotic tool. In contrast, in the second state, the diameter of the incision orifice is larger than the tool diameter. The second case offers more space where the surgical instrument moves freely without constraints before touching the incision wall. The proposed method combines two tasks that must operate hierarchically: i) respect the RCM or UCM constraints formulated by equality or inequality, respectively, and ii) perform a surgical assignment, e.g., scanning or ablation expressed as a 3D path-following task. The proposed methods and materials were tested first on our simulator that mimics realistic conditions of middle ear surgery, and then on an experimental platform. Different validation scenarios were carried out experimentally to assess quantitatively and qualitatively each developed approach. Although ultimate precision was not the goal of this work, our concept is validated with enough accuracy (inferior to 100 micrometres) for ear surgery.