Attitude Magnetic Measurement Compensation Method of Fiber-Optic Submarine Seismometer

When the optical fiber submarine seismometer is applied to the seabed, the direction of vibration should be compensated by heading angle. In order to meet the stringent requirements of small size and low power consumption, geomagnetic sensors are used to measure the heading angle. Due to the complexity of magnetic field interference in the seismometer, the heading angle calculated by electronic compass based on the geomagnetic sensors is not accurate. In order to improve the accuracy of heading angle, we propose a geomagnetic compensation method based on unscented Kalman algorithm, which can solve the problems of difficult calibration operation and long-term accuracy in existing magnetic compensation methods. Meanwhile, according to the environmental conditions of underwater applications, we further optimize the method to reduce the calculation amount and avoid the non-positive definite problem of some Cholesky decomposition. The experiment is carried out to validate the effectiveness of the proposed method. The results show that the heading angle errors compensated by proposed method are all within 0.5°, which meets the application requirements of fiber optic submarine seismometer. In addition, the experimental operation is simple when using the proposed method.