An Arc-Shaped Rotating Magnet Solution for 3D Localisation of a Drug Delivery Capsule Robot

Abstract

A method to estimate the three-dimensional (3D) position of a capsule robot used to deliver drugs in the gastrointestinal tract is proposed in this paper. By exploiting the unique characteristics of the rotating magnetic field created by an array of tangentially magnetised arc-shaped permanent magnets (ASMs), and its analytical formulation, a capsule robot equipped with on-board Hall-effect sensors can measure the rotating magnetic fields created to infer its pose. Extensive validation results provided from a small rotating ASM experimental rig built to test the concept, and a complementary robotic setup for large scale testing are supplied. Given the proven homothetic transformations of magnetic fields, this work demonstrates with validated practical experimentation in a scaled-down rig (1/10), that a full rotation of the ASMs about one axis is sufficient to obtain a mean pose error <; 10 mm in a magnetic system operating in scaled workspaces up to 250 mm, relevant for clinical use of capsule robots inside human bodies.