A Calibration Method for the Misalignment Error Between Inertial Navigation System and Tri-Axial Magnetometer in Three-Component Magnetic Measurement System

Abstract

In order to calibrate the misalignment error between inertial navigation system and tri-axial magnetometer in the three-component magnetic measurement system, a novel calibration method is proposed in the paper. Considering that the magnetometer error is inevitable, the calibration of which is the prerequisite to misalignment error calibration. Therefore, the calibration models of magnetometer error and misalignment error are established firstly, based on which, the objective function is constructed to calibrate the misalignment error. The magnetometer error calibration is based on the principle that the norm of the magnetic survey data keeps constant during the process of solving the objective function. Hence, the objective function solving problem is considered as the equality constrained nonlinear optimization problem, that is, the MATLAB's FMINCOM function is used to solve the objective function. The feasibility and validity of the proposed method were verified by simulation and field experiment, the results of which indicate high accuracy in misalignment error calibration. In the field experiment, the range of x, y, z components are decreased to 1.34%, 1.75% and 1.77% while the absolute errors are reduced to 2.13%, 2.11% and 3.47% respectively after calibration. Method comparisons indicate that the proposed method is superior to traditional methods, which can guarantee the accuracy for three-component magnetic measurement.