Design and Implementation of 3D Positioning Algorithms Based on RF Signal Radiation Patterns for In Vivo Micro-robot

Recent popularity of capsule endoscopes as a medical means to investigate lesions along digestive tract has prompted complaints by doctors about the in sufficient positioning system for the capsules. The possible major reason would be that current positioning system is based on time difference of arrival whose precision is hard to improve for short flight distances. To enable better control of active capsules, we propose to exploit the radiation patterns of radio frequency (RF) signals from the capsules. The symmetric RF signals can be sensed by receivers in similar areas of external receiver arrays. The similarity, position, shape and size of those areas are considered to make back projection calculation and identify accurate 3D positions of the signal source. Our positioning algorithms are scalable to achieve better precision than the density of receivers.