Calibration function estimation using 3D interpolation for indoor EM (electromagnetic) location finding system

Indoor location finding using electromagnetic field strength measurement is one of the methods being used in different applications in recent years. There are two main problems/ challenges in the direct current electromagnetic (EM) accurate location devices which are used for indoor location. First, the changing of positioning data received is not linear when sensors are moving linearly. Second, the distribution of accuracy varies in different places which leads to large positioning error in some areas. In this paper a 3D surface fitting is explored and a location calibration function is estimated, which built the bridge between EM coordinates and the geometric coordinates for received location data and accuracy is comparable to 1 cm. Experiments and simulation showed that accuracy.