A Novel Magnetic Tracking Approach for Intrabody Objects

Magnetic-based localization technique has been widely studied to provide accurate position and orientation information of intra-body objects, such as capsule endoscopes. However, the magnetic field decays rapidly, which is inversely proportional to the cubic of the distance. As a result, the tracking range is limited. In this paper, a magnetic servo approach is proposed for intra-body objects that move in a large volume, such as the whole digestive tract. A static tracking system formed with 8 Hall sensors is linked with a movable platform with motors. The proposed method utilizes the static tracking system to provide a precise positioning result within a small tracking range. When the distance between the object and the static tracking system exceeds a certain threshold, static tracking system will be controlled by the motors to move automatically based on a magnetic servo method to ensure accurate tracking results in a large range. Experimental results show that the proposed servo tracking method can provide a high accuracy of positioning and orientation results within a large range that as good as stationary method in small range. Within the range of 600 mm \times500 mm, the average position error is 2.04 mm and orientation error is 2.45°. The proposed localization method would be beneficial to the clinical examination and navigation.