Hybrid 6-DoF Magnetic Localization for Robotic Capsule Endoscopes Compatible With High-Grade Magnetic Field Navigation

Abstract

The paper proposes a hybrid 6 degrees of freedom localization system for endoscopic magnetic capsules, compatible with external high-grade permanent magnetic locomotion. The proposed localization system, which is able to provide an accurate estimation of the endoscopic capsule pose, finds application in the robotic endoscopy field to provide efficient closed-loop navigation of a magnetically-driven tethered capsule. It takes advantage of two optimization steps based on a triangulation approach, i.e. (1) mathematical approximations of the magnetic field, and (2) minimization of the magnetic field mean square deviation. The proposed localization system was tested in two different in-vitro scenarios for mimicking the clinical cases that a magnetic capsule would encounter during tele-operated magnetic navigation. The development phase was preceded by an in-depth work-space analysis to lay the groundwork for the localization design and implementation. Results of the hybrid 6 degrees of freedom localization system show a significant accuracy in accordance with the state-of-the-art, i.e. about 5 mm in position and 5° in orientation, but introducing benefits in expanding the work-space by increasing the number of electromagnets onto the operating table, as an independent solution with respect to the external magnetic locomotion source.

Keywords

• Capsule endoscopy
• magnetic-based navigation and localization
• magnetic field models
• minimally-invasive colonoscopy
• robotic endoscopy