An improved magnetic localization and orientation algorithm for wireless capsule endoscope.

In this paper, we propose a novel localization algorithm for tracking a magnet inside the capsule endoscope by 3-axis magnetic sensors array. In the algorithm, we first use an improved linear algorithm to obtain the localization parameters by finding the eigenvector corresponding to the minimum eigenvalue of the objective matrix. These parameters are used as the initial guess of the localization parameters in the nonlinear localization algorithm, and the nonlinear algorithm searches for more appropriate parameters that can minimize the objective error function. As the results, we obtain more robust and accurate localization results than those by using linear algorithm only. Nevertheless, the time efficiency of the nonlinear algorithm is enhanced. The real experimental data show that the average localization accuracy is about 2mm and the average orientation accuracy is about 1.6 degrees when the magnet moves within the sensing area of 240 mm x 240 mm square.