Differential Geomagnetic Compensation Method for the Static Magnetic Localization of Capsule Endoscopes During Activities of the Daily Life

Static magnetic localization is widely employed to localize capsule endoscopes. A permanent magnet is integrated into the capsule, and a sensor array outside the body measures its magnetic field. However, the geomagnetic flux density distorts the localization when no compensation method is applied. In this study, an optimized differential geomagnetic compensation method is proposed. A sensor array adapted to the typical abdomen size with 12 equally oriented sensors was used. The sensors are grouped into 26 pairs, and by subtracting the measured values of those, the geomagnetic field cancels out. This method was experimentally evaluated within a localization region of the size of a typical gastrointestinal tract. Static and dynamic scenarios in domestic environments were applied to evaluate the system in daily life situations. Moreover, the magnet was continuously moved, while the traveled distance was recorded. The mean position and orientation errors for the static and dynamic scenarios did not exceed 4 mm and 2°, respectively. Furthermore, the traveled distance of the magnet was tracked with an accuracy of 3.4 mm. Therefore, it was revealed that the proposed system is applicable in daily life scenarios and capable of precisely tracking the traveled distance of the capsule inside the intestine to locate abnormalities. Overall, the results significantly outperform state-of-the-art methods.