Notice

Successful Centimeter-Level Positioning of the Deep Seafloor Using a UAV

— Achieving high-speed, highly maneuverable seafloor observation without reliance on ships or buoys —

Hama k.k. (Head Office: Minamisoma City, Fukushima Prefecture; President & CEO: Masata Kaneda) has succeeded—in collaboration with Associate Professor Yusuke Yokota of the Institute of Industrial Science (IIS), The University of Tokyo—in high-precision positioning of the deep seafloor using a seaplane-type unmanned aerial vehicle (UAV).

In this experiment, we achieved, for the first time in the world, centimeter-level positioning of the seafloor at depths of 1,000 m or more, using a UAV that alights on the sea surface. Compared with conventional vessel- or buoy-based observation, this enables higher-frequency and lower-cost seafloor measurements.

The technology is especially promising as a new means for rapid, high-precision monitoring of crustal deformation for earthquake-disaster countermeasures, such as those related to the Nankai Trough megathrust.

Research Overview

Seafloor observation has traditionally required large research vessels and buoys, presenting challenges in cost (often ¥1,000,000+ per day) and mobility (typical vessel speed is about 20 km/h). Buoys also struggle to maintain position on the sea surface, limiting the feasibility of frequent observations.

In our work, we realized centimeter-level seafloor positioning by employing the seaplane-type UAV “HAMADORI6000” (developed by Hama k.k.) and combining a GNSS antenna with an acoustic sonar.

The UAV has a 6.3 m wingspan, is gasoline-engine powered, reaches a maximum speed of 90 km/h, and offers a range of approximately 330 km, delivering far greater mobility than vessels. By selectively using commercial off-the-shelf (COTS) components, we also succeeded in reducing the overall cost of observation instruments.

Experimental Results

• Tank tests at IIS, The University of Tokyo confirmed distance-measurement accuracy within approximately 2 cm.
• Field experiments in Sagami Bay achieved centimeter-level accuracy comparable to vessel-based measurements.

These results demonstrate the feasibility of rapid, low-cost detection of seafloor deformation without deploying ships.

Future Prospects

This technology is applicable both to rapid post-earthquake seafloor surveys and to long-term monitoring. We will continue advancing system refinements to ensure robust operation even under non-ideal wind and sea states.

Related Information

• Press Release (November 18, 2022)
  “Successful Deep-Seafloor Observation by a UAV Alighting on the Sea Surface”
  https://www.iis.u-tokyo.ac.jp/ja/news/4047/
• Video: UAV performing observation on the sea surface
  https://youtube.com/clip/Ugkxfs5FPOu9b8lIr040WgmN8RQnYJiG9GsQ?feature=shared
• Related Paper
  Journal: Earth and Space Science
  Title: Construction and Demonstration of a Seaplane-type UAV-based High-Precision GNSS-A Seafloor Crustal Deformation Observation System
  DOI: 10.1029/2025EA004237

Inquiries

Hama k.k.
General Affairs Department — Takayuki Hanaoka
Tel: (+81)244-26-6208
E-mail: info@hamakk.jp
URL: https://www.hamakk.jp/