Precise Underwater Localization Using Sonar and Electro-Optics (PULSE)

Underwater ship hull inspection platforms routinely check for damage, corrosion, and suspicious objects. Highly accurate position information is required to properly register hull inspection data with previously collected data to monitor the progression of structural anomalies and other changes and ensure complete hull coverage. Conventional underwater localization methods are inadequate for hull inspection. For example, fixed-source signal triangulation systems do not function well in shallow water, and inertial dead-reckoning systems accumulate unacceptable error over time. Alternative vision-based techniques, such as simultaneous localization and mapping (SLAM), have shown some promise for underwater platforms. However, the underwater environment and hull inspection task present several challenges to these techniques, such as poor visibility and limited scene structure. We propose Precise Underwater Localization Using Sonar and Electro-Optics (PULSE), an approach that uses optical and acoustic imaging sensors to offer greater flexibility under these conditions. In our preceding Phase I effort, we demonstrated the concept of underwater SLAM using a video camera and imaging sonar together. In this Phase II effort, we will enhance the PULSE system by introducing a stereo camera and 3D sonar to improve navigation accuracy, and perform extensive testing over a wide range of representative operational environments and scenarios.