Persistent Localization of Autonomous Underwater Vehicles Using Visual Perception of Artificial Landmarks

Persistent localization is a critical requirement for autonomous underwater vehicles (AUVs) engaged in long-term missions. Conventional dead-reckoning (DR) methods for estimating the position and orientation of AUVs often suffer from drift, necessitating additional information to correct accumulating errors. In this paper, we propose a visual artificial landmarks-based simultaneous localization and mapping (SLAM) system for AUVs. This system utilizes two types of underwater artificial landmarks that are observed using forward and downward-looking cameras. The information obtained from these detected landmarks, along with incremental DR estimates, is integrated within a framework based on the extended Kalman filter (EKF) SLAM approach, allowing for the recursive estimation of both the robot and the landmark states. We implemented the proposed visual SLAM method using our yShark II AUV and conducted experiments in an engineering basin to validate its effectiveness. A ceiling vision-based reference pose acquisition system was installed, facilitating a comparison between the pose estimation results obtained from DR and those derived from the SLAM method.