U-VIP-SLAM: Underwater Visual-Inertial-Pressure SLAM for Navigation of Turbid and Dynamic Environments.

Vision-based autonomous underwater vehicle localization, navigation, and mapping is an attractive field of research in recent years. Despite the development of vision-only and vision-inertial-based algorithms, particularly in the terrestrial and aerial robotics groups, applying such approaches directly to underwater environments remains challenging due to visual degradation in the medium and further due to the slow crusade of the underwater vehicles. This paper introduces U-VIP-SLAM, a unique visual-inertial-pressure SLAM system that combines data from a monocular camera, a low-cost IMU, and a pressure sensor to create a SLAM system focused to the underwater region. All of the key components of a comprehensive SLAM system are included in the U-VIP-SLAM, including loop closure capabilities tailored to the underwater environment. Further, we introduce forward and backward projection strategies to fuse pressure measurement in the local bundle adjustment. Furthermore, a unique initialization strategy is proposed to effectively bootstrap the system by fusing pressure and IMU data. Several datasets were used to compare the performance of the proposed methods against the state-of-the-art monocular VI systems. Source Code is available at https://github.com/chintha/U-VIP-SLAM.git. [ABSTRACT FROM AUTHOR]