Six Degrees of Freedom Tracking and Wireless Charging for Capsule Endoscopy

Capsule endoscopy is an emerging technology providing a noninvasive approach to diagnose and monitor gastrointestinal (GI) diseases. However, this technology has fundamental limitations of short-range of investigation due to limited battery capacity and uncertain position of the capsule inside the GI tract. This research work attempts to address these two critical issues using a novel approach to seamlessly combine wireless battery charging, and six degrees of freedom (6DoF) tracking of capsule endoscopy on a single apparatus. A full-scale complete prototype is presented in this article, wherein the receiving coil is integrated in a fully functional capsule, and the transmitting coil is able to accommodate an adult human body. In the tracking operation, a gradual dc magnetic field is generated in the transmitting coil. The magnetic field intensity surrounding the capsule is measured and consolidated with inertial measurement to identify the capsule's position and orientation. In the evaluation, the maximum mean absolute error for attitude angles and position are less than 3.80${}^{\circ}$ and 2.07 mm, respectively. A relatively uniform ac magnetic field will be generated while a low battery is detected. During wireless charging, the capsule receives 376.08 mW of power, resulting in an estimated charging rate of 2C for the capsule battery.