Autonomous underwater vehicle homing/docking via electromagnetic guidance

Central to the successful operation of an autonomous undersea vehicle (AUV) is the capability to return to a dock, such that consistent recovery of the AUV is practical. A number of homing technologies have been proposed and tested, with acoustic homing generally the most prevalent. Accurate acoustic homing requires systems with high update rates, and extensive signal conditioning if AUV orientation is required, as well as, bearing and distance to the dock. Vehicle orientation becomes increasingly important in the final stages of the docking, as large changes in orientation near the dock are impractical and often not possible. An electromagnetic (EM) homing system is one alternative that can provide accurate measurement of the AUV position and orientation to the dock during homing. This system offers inherent advantages in defining the AUV orientation, when compared to high frequency acoustic systems. The design and testing of an EM homing system is given, with particular attention to one can be adapted to a wide class of AUVs. The EM homing system consists of a dock with EM coils that provide the homing signal, and set of sensing coils that are mounted in the AUV. The present tests used the MIT Sea Grant Program Odyssey AUV as the test vehicle. A number of homing, docking and latching trials were successfully performed with the design. Homing data include dead reckoning computation and acoustic tracking of the homing track, and video documentation of homing into the dock