Calibration Improvement of Three-axis Magnetometer in Disturbing Magnetic Circumstance Based on FIR Digital Filter

Ideally, the output total value of three-axis magnetometer is stable at a certain place no matter what direction the three-axis magnetometer is placed. Actually, diversionary error of the three-axis magnetometer can not be avoided. In stable magnetic circumstance, tradional LMS adaptive algorithm is with good performance to calibrate the three-axis magnetometer. Experiment result indicates that diversionary error is decreased from 28nT to 3.5 nT; but the performance is had in disturbing magnetic field circumstance. Hence, the new method of combining adaptive filter with FIR digital filter is introduced. Then, advantages of the new method is proved by comparing with traditional LMS adaptive filter. Original diversionary error of three-axis magnetometer is 34.4722 nT in disturbing magnetic field circumstance, which is calibrated to 25.7352 nT using traditional LMS adaptive filter and 2.3502 nT by the new method of combining adaptive filter with FIR digital filter, respectively. Obviously, the method proposed in this paper has better calibration performance in disturbing magnetic circumstance.