Magnetic Tracking of Wireless Capsule Endoscope in Mobile Setup Based on Differential Signals

Magnetic localization methods have been widely studied to provide accurate position and orientation information of intra-body objects, such as wireless capsule endoscopes. However, these methods cannot work well in dynamic scenarios when using a wearable sensor array due to the geomagnetic field. In this article, we propose a novel approach for tracking wireless capsules in a mobile setup based on differential signals from adjacent magnetic sensors. Compared to the previous passive magnetic localization framework, the proposed algorithm can eliminate the interference of the geomagnetic field without introducing other compensation sensors or signals. As a result, the proposed method can be used for wearable sensor arrays without knowing the distribution of the geomagnetic field and the movement of the sensor array in advance. Moreover, the relationship between position error and distance of adjacent sensors has been studied to improve tracking accuracy. Finally, a sensor array with 16 three-axis magnetic sensors is developed. Both static and dynamic experiments have been carried out, whose results verified the effectiveness of the proposed method.