The calibration of 3-axis magnetic sensor array system for tracking wireless capsule endoscope

A magnetic localization and orientation system is proposed for tracking wireless capsule endoscope. This system uses a small magnet enclosed in the capsule to serve as excitation source. When the capsule moves, the magnet establishes a static magnetic field around. With the magnetic sensor array composed of Honeywell 3-axis magnetic sensors, HMC1053, the magnetic intensities in some pre-determined spatial points can be detected, and the magnet's position and orientation parameters can be computed based on an algorithm. To initiate the system and obtain better tracking accuracy, we propose a calibration technique for the magnetic tracking system. The calibration includes sensitivity determination and nonlinearity adjustment, sensor center position and orientation adjustment. Based on the calibration procedures, the system can achieve satisfactory tracking accuracy with the average localization error 3.3 mm and the average orientation error 3.0 degrees.