The Electronic Compass Measurement Error Analysis And Compensation Techniques

Based on practical measurement of electronic compass will exist error inevitably, this paper puts forward the electronic compass error calibration and compensation method after analyzing the mechanism of error.Electronic compass can be divided into three axis magnetic sensor manufacturing error,installation error and carrier magnetic error based on the error of generating mechanism. However, three axis magnetic sensor manufacturing error include zero bias,sensitivity mismatch and angles which are not orthogonal, carrier magnetic error include hard magnetic interference error and soft magnetic interference error. Therefore, the mathematical model of manufacturing error,installation error mathematical model and carrier magnetic error model are established on the analysis of each error's effect to the measure result of magnetic sensor.In this paper, least square fitting method based on ellipse constrained is proposed for error model. Ellipse constraint conditions are determined according to the nature of ellipse, and then transforming the problem of solving elliptic parameters into calculating the extremum under constraint conditions. Finally, determining the fitting elliptic parameters, generalizing the ellipse fitting method to three-dimensional space and proposing least square fitting method based on ellipsoid constrained.This paper introduces the calibration method of electronic compass error parameters in detail which based on the error model and ellipse fitting ellipsoid, derives the formula for calculating the error parameters, proposes manufacturing error, installation error/angle of dip, carrier magnetic field error compensation method .For the original three-dimensional magnetic field data measured by electronic compass, followed by the order of manufacturing error compensation, installation error/angle of dip compensation, carrier magnetic field compensation error compensation in electronic compass, and to eliminate the deviation with the values of the ideal three-dimensional magnetic field data.At last, this paper designs the electronic compass error calibration and compensation software which based on MATLAB and designs the appropriate test, calibration error of parameters of electronic compass, tests and verifies the correctness and effectiveness of error compensation in the environment of the turntable and applies it in the automotive environment.