Two-step compensation via rotational stepping error fitting for precise azimuth measurement with electronic compass

Abstract

Marine buoys commonly employ electronic compasses to measure their azimuth angles under the requirements for low power consumption and high precision. After installation on buoys, geomagnetic electronic compasses often suffer from measurement errors in azimuth angles due to manufacturing errors and magnetic interference from the buoy structure. This paper presents a two-step compensation method for azimuth measurement errors of electronic compass based on rotational step error fitting. In the first step, before installation on the buoy, the magnetometer of the electronic compass is calibrated using the ellipsoidal fitting method, which requires arbitrary rotation of the lightweight compass around multiple different axes. In the second step, after mounting the electronic compass inside the buoy, stepwise rotations are performed to collect azimuth measurement errors at various angles. The least squares method is then applied to fit the developed error function relative to rotation angle to generate compensation values for various azimuths, which are used for secondary error compensation. Experimental results demonstrate that using azimuth angles calculated by high-precision satellite positioning devices as absolute reference values, the measurement accuracy of azimuth angles reaches 0.6° after applying the proposed compensation method to the electronic compass. This approach avoids the use of three-dimensional rotation operations or large Helmholtz coils and is therefore simple and suitable for field operation.