Innovative Differential Magnetic Localization Method for Capsule
Endoscopy to Prevent Interference Caused by the Geomagnetic Field
Abstract
Wireless capsule endoscopy is an established medical application for the
examination of the gastrointestinal tract. However, the robust and
precise localization of these capsules is still in need of further
scientific investigation. This paper presents an innovative differential
magnetic localization method for capsule endoscopy to prevent
interference caused by the geomagnetic field. The effect of changing the
orientation of the capsule on the localization process was also
examined. Simulations using COMSOL Multiphysics with the superimposed
geomagnetic field were performed. The Levenberg–Marquardt algorithm was
applied in MATLAB to estimate the position and orientation of the
capsule. Comparing the proposed differential method with the absolute
magnetic localization method under ideal conditions, the mean position
and orientation errors were reduced by three orders in magnitude to less
than 0.1 mm and 0.1 ° respectively. Even if sensor non-idealities are
considered, the simulationbased results reveal that our proposed method
is competitive with state-of-the-art geomagnetic compensation methods
for static magnetic localization of capsule endoscopes.The achieved
localization accuracy by applying the differential method is not
dependent on the rotation of the localization system relative to the
geomagnetic flux density under the made assumptions and the impact of
the magnet orientation is neglectable. It is concluded that the proposed
method is capable of preventing all interference whose components are
approximately equal at all sensors with identical orientation.