Dual-attention-based optical terminal guidance for the recovery of unmanned surface vehicles

Abstract With the outstanding performance of unmanned surface vehicles (USVs) in maritime missions with scientific and commercial applications, increasing numbers of ships have begun to carry USVs to perform tasks. For the autonomous recovery of a USV along a preset trajectory to the docking station under various sea conditions, we propose a new navigation strategy with dual-attention-based optical terminal guidance. Monocular vision systems with creatively designed identification light sources are mounted on the docking station and USV, respectively. Thus, the azimuth angle, heading angle and relative distance between the docking station and the USV can be accurately measured. This method achieves centimeter-level homing accuracy and a 0.1-degree angle measurement error. A tracking control algorithm based on a line-of-sight method is suggested , and the control quantity of the USV is directly generated. Sea trials were conducted under various weather conditions to validate the proposed algorithm. This method provides reliable USV guidance to the docking station with a stern ramp from the maximum capture distance of approximately 100 meters. The proposed dual-attention method provides convenient implementation and transplantation to various unmanned platforms.