Prodrone, KDDI SmartDrone, and IDEAC Successfully Demonstrate Remote Automated Underwater Breakwater Inspection Using an Air-and-Water Drone

Prodrone Co., Ltd., KDDI SmartDrone Inc., and IDEAC Co., Ltd. announced that on March 24, 2026, they successfully completed a demonstration experiment using an “air-and-water integrated drone” capable of both flying and diving. The drone was remotely operated from land and automatically inspected the underwater section of a breakwater. By establishing this technology, the companies aim to enable safer and lower-cost maintenance of aging port infrastructure, replacing some underwater inspection work currently performed by divers, who are in severe shortage. The demonstration was developed and conducted under a project commissioned by Japan’s Ministry of Land, Infrastructure, Transport and Tourism: “Technology development and demonstration for improving the efficiency of port facility inspection and surveying using drones,” under the Small and Medium Enterprise Innovation Creation Promotion Program. Many port facilities in Japan were built during the country’s period of rapid economic growth. By 2040, about 70% of these facilities are expected to be more than 50 years old. At the same time, the divers responsible for underwater inspections are aging, and the shortage of successors is widening the supply-demand gap. Underwater inspections in shallow waters involve multiple risks, including visibility, currents, and residual pressure management, making it necessary to build a sustainable inspection system that is both safe and cost-efficient. In this demonstration, the team successfully completed a full operation sequence: remotely controlling the drone from land, automatically flying it to the target sea area, landing on the water, diving, and autonomously navigating underwater to inspect the breakwater. The key feature of the project is that it achieved remote automated underwater inspection at low cost. Underwater autonomous navigation for applications such as seabed resource exploration typically requires expensive devices such as INS inertial navigation systems or DVL Doppler velocity logs. In this development, however, the team used KDDI’s high-precision acoustic positioning technology, cultivated through maintenance and inspection of submarine communication cables, to achieve stable underwater autonomous navigation without those high-cost devices. The demonstration took place at Morozaki Port in Minamichita, Aichi Prefecture. At an offshore breakwater, the team verified whether acoustic positioning-based underwater autonomous navigation could capture the underwater section of the breakwater completely and efficiently. The procedure included automatic flight and water landing by the aerial drone, separation and automatic diving of the underwater drone, autonomous navigation and imaging along preset waypoints, recovery of the underwater drone, and automatic return flight to land. The result showed that the system could capture the breakwater wall completely and efficiently without being swept away by tidal currents, demonstrating that drone-based inspection can replace diver-based underwater inspection at a lower cost. Going forward, the three companies will continue developing underwater autonomous navigation technology for the air-and-water integrated drone, aiming to create a society where hazardous underwater work can be performed more safely and at lower cost. Beyond underwater port infrastructure inspection, they plan to apply the technology to rapid underwater damage assessment after disasters, as well as fisheries applications such as fixed-net and aquaculture site monitoring, while continuing technical development and demonstrations toward early practical deployment and social implementation. The air-and-water integrated drone combines an aerial drone and an underwater drone, enabling both flight and underwater operation. Through LTE mobile communications, it supports remote autonomous navigation in the air, on the water surface, and underwater. In addition to underwater imaging, it can be equipped with a multibeam sonar for seabed measurement or an SLR camera for aerial inspection of water infrastructure. Its basic specifications include a size of 1,670 mm × 1,670 mm × 665 mm, weight of 31 kg, payload of 15 kg, wind resistance of 10 m/s, IP55 water resistance, 15 minutes of flight time when carrying the underwater drone, approximately one hour of diving time depending on currents, and a 70-meter cable. The system’s autonomous navigation uses acoustic positioning technology developed by KDDI. Signals from an acoustic transmitter mounted on the underwater drone are received and analyzed by acoustic receivers installed in the aerial drone above the water, allowing the system to measure distance and direction between the drones. By distributing four acoustic receivers across the legs of the aerial drone and applying proprietary signal processing technology, the system improves positioning accuracy and enables stable positioning even near breakwaters with substantial acoustic reflections. The technology is expected to be used for underwater infrastructure inspection of port facilities, offshore wind power facilities, dams, and bridge piers. It can also support disaster response by assessing damage to port mooring facilities and filming sunken vessels, as well as regular underwater monitoring of fixed nets and aquaculture sites without deploying boats or divers. In the development structure, Prodrone is responsible for product planning and development, KDDI SmartDrone oversees integration and overall implementation of the acoustic positioning technology on the aircraft, KDDI Research developed the acoustic positioning technology, and IDEAC is responsible for port facility inspection methods.