Impact and remediation of misalignment between shipborne triaxial geomagnetic measurements and attitudinal changes

In the process of calibrating shipborne geomagnetic vector measurement systems, numerous challenges are usually faced, such as internal sensor and installation errors, interference from the ship's structure, among others. It's commonly believed that the asynchrony (misalignment) between geomagnetic components and attitude changes has a negligible impact on the overall error and thereby can be disregarded. However, this work proposes that the asynchrony between geomagnetic components and attitude information significantly affects the precision of computation, especially in the Z component, based on in-depth analysis of the actual shipborne triaxial geomagnetic data from the ‘TAN KAH KEE’ research vessel. To address this mismatch a new method is proposed, based on the similarity between the attitude waveforms of the inertial navigation system and the geomagnetic component waveforms in specific headings. The asynchrony is effectively removed through the adjustment of the geomagnetic component data waveform, and its successful synchronization with the attitude data waveform. The analysis of the processed data reveals a significant reduction in the mean square errors of the northward, vertical, and eastward components of the geomagnetic field, as well as the total field, from 60.25nT, 204.19nT, 86.72nT, and 77.82nT to 57.36nT, 59.16nT, 62.91nT, and 58.75nT, respectively. This substantial decrease in the error fully validates the need and applicability of the proposed synchronization matching method. Additionally, it allows for lower-cost shipborne geomagnetic measurements, with independent operational devices.