Analysis of three-dimensional maximum likelihood algorithm for capsule endoscopy localization

Wireless capsule endoscopy (WCE) has become a good therapeutic method for a period of time. It helps detect, exam and heal gastro-intestinal (GI) related diseases. In the Capsule endoscopy application, knowledge of capsule position inside human body is rather important because it enables doctors locate the tumor of bleeding inside GI track and prepare for further therapeutic operations. However, due to the harsh environment for in-body wireless channel, in-body localization remains difficult and erroneous. In this paper, an improved three dimensional maximum likelihood algorithm has been introduced based on received signal strength (RSS) localization technology. Human body mesh and GI track mesh are built as the environment of algorithm simulation. Algorithm performance has been evaluated by comparison with the Cramer-Row Lower Bound (CRLB) and ranging error of the algorithm varies from 25mm to 140mm. By analyzing the results, we conclude that the three dimensional maximum likelihood is heavily impacted by the distance between implant and base station and its performance can be further improved.