Fusion of fluxgate sensors with navigational data for the improvement of the detection of underwater metal-containing objects

With the underwater human activity actively developing and the rise of the autonomous unmanned underwater vehicles (AUV) industry, researchers and engineers face the task of maintenance and repair of communications. For this purpose AUVs can be used, with e.g. the task of inspecting pipelines. The article describes the processing algorithm for the signal from passive ferromagnetic (fluxgate) sensors mounted on an AUV carrier used to search for metal-containing objects at the sea bottom. A scheme for such a measurement is proposed - the installation of two sensors at the opposite ends of the carrier. This allows to measure the gradient of magnetic field between the sensors. The characteristic form of such a signal and the dependence of the signal on the motion parameters of the vehicle and external factors are determined. To eliminate false positives, filters are used based on the readings of the position, speed and orientation sensors of the navigation system. Using data on the motion parameters of the device allows to generate a reference signal, which is used to validate the detection of an object using the cross-correlation method. The use of data on orientation angles makes it possible to compensate for the influence of the orientation of the device in the Earths magnetic field.