Magnetic gradiometer on an AUV for buried object detection

Magnetic detection is an effective way for underwater buried target detection especially man-made objects which will contain some amount of permeable materials. Magnetic sensing can augment acoustic means of detection, effectively reduce false alarms. The advances in Autonomous Underwater Vehicle (AUV) technology enabled the integration of magnetic gradiometer onboard for underwater buried object detection. In this paper, the design considerations and configurations of a prototype magnetic gradiometer integrated to an AUV and the magnetic data fusion with AUV navigation data will be presented. The magnetic gradiometer formed by fluxgate magnetometers has several advantages such as small size and low power with relatively high sensitivity. Magnetic noise compensation is also critical as the magnetometer has to operate close to the AUV magnetic noise sources. The paper will describe the results of the platform magnetic noise compensation and sea trial measurements.