Novel Method for Tracking Mooring Lines of Floating Offshore Wind Turbines Using Autonomous Underwater Vehicle

Strategic Insights -

Researchers from the University of Tokyo have developed a novel method for tracking mooring lines of Floating Offshore Wind Turbines (FOWTs) using an Autonomous Underwater Vehicle (AUV) equipped with a tilt-controlled Multibeam Imaging Sonar (MBS). This approach enables the AUV to estimate the 3D positions of mooring lines and safely track them in real-time, overcoming the limitations of traditional Remotely Operated Vehicle (ROV)-based inspections. The study, funded by the New Energy and Industrial Technology Development Organization (NEDO), has been peer-reviewed and published in the Journal of Field Robotics.

Key Takeaways:

  • The proposed method allows the AUV to estimate the 3D positions of mooring lines and track them in real-time, enhancing the safety and efficiency of FOWT inspections.
  • The research utilized a tilt-controlled MBS and a pre-trained You Only Look Once (YOLO) model to identify mooring lines within sonar imagery, adjusting the AUV's velocities to maintain a safe distance during inspection.
  • The study demonstrated the feasibility of using the proposed method in both tank experiments and a sea experiment conducted at the FOWT Hibiki in Kitakyushu, Japan, where the AUV successfully tracked the mooring lines for 423 s.
  • The research highlights areas for future improvement, including enhancing localization accuracy, developing robust control algorithms, and expanding the analysis of mooring line conditions.
  • The proposed method lays the groundwork for future advancements in automated mooring line inspections and enables the integration of additional techniques, such as visual inspection.
  • The study was conducted by researchers Sehwa Chun, Hiroki Yokohata, Kenji Ohkuma, Toshihiro Maki, Shouhei Ito, and Shinichiro Hirabayashi.
  • The research received funding from NEDO.

Statistics:

  • The AUV successfully tracked the mooring lines for 423 s in the sea experiment.
  • The study utilized a tilt-controlled MBS and a pre-trained YOLO model for identifying mooring lines.
  • The proposed method enables the AUV to estimate the 3D positions of mooring lines with enhanced accuracy.

Sources:

  • Tracking Mooring Lines of Floating Structures By an Autonomous Underwater Vehicle. Journal of Field Robotics, 2025.
  • Journal of Field Robotics. Wiley, 111 River St, Hoboken 07030-5774, NJ, USA. (Wiley-Blackwell - www.wiley.com/; Journal of Field Robotics - onlinelibrary.wiley.com/journal/10.1002/(ISSN)1556-4967)
  • NewsRx. New Field Robotics Study Findings Have Been Reported by Investigators at University of Tokyo (Tracking Mooring Lines of Floating Structures By an Autonomous Underwater Vehicle). Robotics & Machine Learning. October 27, 2025; p 257.