DOI: 10.1184/r1/7584005
title: Localization, Calibration, Control, and Design of Magnetically Actuated Soft Capsule Endoscopes

description: Current medical technologies are converging to minimally invasive diagnosis and therapy.<br>The effort to reduce patient discomfort in gastrointestinal (GI) tract diagnoses resulted in the<br>development of wireless capsule endoscopes (WCEs). In the form of a pill, a camera carrying<br>WCE travels through the GI tract by natural peristalsis while it collects images of the internal<br>wall of the GI tract. The operation might be entirely painless. However, their inability to have<br>active locomotion and control limit detailed diagnoses, therapeutic functions, and minimization<br>of the operation time. Actively controlled WCEs would resolve those challenges.<br>This thesis provides methods for the active control of WCEs using magnetic interactions,<br>and applies those methods to a robotic biopsy capsule endoscope. First, a localization method<br>for meso-scale magnetic robots is developed. The method utilizes a magnetic sensor array<br>where a magnetically actuated capsule endoscope (MACE) does not require a special device<br>for localization but a single magnet. The method is beneficial to reduce the size and the battery<br>consumption of the MACE. The method focuses on decoupling the magnetic field of the<br>MACE from the magnetic field of the actuator, and developing a real-time localization algorithm.<br>Second, an automatic calibration method for magnetic actuation and sensing systems<br>is presented. The method calibrates a number of nonlinear magnetic sensors and a number of<br>electromagnets. The method is capable of calibrating 1.8k parameters in an exemplary system<br>in a reasonable time without human labor. In this work, Bundle Adjustment framework from<br>Computer Vision is modified and adapted to magnetic robot sensing and actuation systems.<br>This work would be useful for a magnetic system which requires frequent reconfiguration or<br>sensor/actuator gain updates. Third, control methods for a meso-scale magnetic robots on a<br>surface with non-uniform magnetic field actuations are presented. The control methods utilize<br>magnetic energy wells to cope with a low actuation bandwidth compared to the fast dynamics<br>of the capsule endoscope. Additionally, we present a teleoperation system to mitigate the orientation<br>coordination difficulty when a person uses the system. Fourth, all of the above three methods are integrated and applied to a magnetically actuated soft capsule endoscope for the<br>biopsy functionality (B-MASCE). We designed a biopsy capsule endoscope with a high diagnostic<br>accuracy by adopting a clinically well established biopsy method called fine-needle<br>capillary biopsy. Ex vivo experiments in a fresh porcine stomach show promising results. In<br>summary, this thesis presents localization, calibration, control methods and their application in<br>a biopsy capsule robot, which are useful for the automation of robotic capsule endoscopes. We<br>envision that, in future, patients have painless GI tract endoscopy and treatment with highly<br>functional robotic endoscopic capsules.<br>