A Full Span Magnetic Localization Algorithm Magnetic dipole is a conventional model for the localization of a magnet. However, a restriction is that the distance from the test field point to the magnetxe2x80x99s position must be long enough comparing with the length of the magnet. Otherwise, the dipole model is inaccurate, which is known as the nearfield problem. In this paper, we investigated the nearfield magnetic density distribution for a circular ring magnet with respect to the magnetxe2x80x99s center, which is simply symmetrical about the magnetxe2x80x99s main axis, so it is in 2 dimensions. Further, we propose the full span (including nearfield) localization algorithm on this distribution, which minimizes the calculation error between the measured flux densities and those calculated from the spatial and rotation transforms from the global coordinate system to the magnetxe2x80x99s coordinate system, so as to compute the magnetic density on the 2D field density distribution. Simulation results show that the proposed method can accurately to obtain the magnetxe2x80x99s position and orientation in nearfield.

RealTime Calibration of Magnetometers Using the RLSML Algorithm This study presents a new realtime calibration algorithm for threeaxis magnetometers by combining the recursive least square (RLS) estimation and maximum likelihood (ML) estimation methods. Magnetometers are widely employed to determine the heading information by sensing the magnetic field of earth; however, they are vulnerable to ambient magnetic disturbances. This makes the calibration of a magnetometer inevitable before it is employed. In this paper, first, a complete measurement error model of the magnetometer is studied, and a simplified model is developed. Then, the realtime RLS algorithm is introduced and discussed in detail, and the unbiased optimal ML is utilized to improve the accuracy of the parameter estimation. The proposed algorithm is advantageous in correcting the parameters in real time and simultaneously obtaining unbiased parameter estimation. Finally, the simulation and experimental results demonstrate that both the accuracy and computational speed of the proposed algorithm is better than those of the widely used bathprocessing method. Moreover, the proposed calibration method can be adopted for calibrating other threeaxis sensors.