Successful demonstration of remote and automatic underwater inspection of a breakwater using a combined hydro-air drone and acoustic positioning device - Establishing a safe and low-cost underwater inspection method to replace divers, realizing port infrastructure DX -

Prodrone Co., Ltd. (Headquarters: Nagoya City, Aichi Prefecture, President and CEO: Shunsuke Toya, hereinafter referred to as Prodrone), KDDI Smart Drone Co., Ltd. (Headquarters: Chiyoda-ku, Tokyo, President and CEO: Masafumi Hirono, hereinafter referred to as KDDI Smart Drone), Ia Co., Ltd. (Headquarters: Setagaya-ku, Tokyo, Representative Director and Chairman: Tabata) On March 24, 2026, the three companies Hideo (hereinafter referred to as "Iade") successfully conducted a demonstration experiment to complete an automatic inspection of the underwater part of a breakwater by remote control from land using a "water-air combination drone" that can fly in the air and dive into water. The establishment of this technology will enable safer and lower-cost infrastructure maintenance and management in place of divers, who are currently facing a serious manpower shortage, in underwater inspections of aging port infrastructure.

This demonstration was developed and implemented under contract with the Ministry of Land, Infrastructure, Transport and Tourism's ``Small and Medium Enterprise Innovation Creation Promotion Project/Technology Development and Demonstration for Improving the Efficiency of Port Facility Inspections and Investigations Using Drones,'' which aims to streamline port facility inspection work using drones.

water-air combination drone

Demonstration situation

Demonstration video

■ Background of the demonstration experimentMany of Japan's port facilities were constructed during the period of high economic growth, and by 2040, approximately 70% of all facilities are expected to be over 50 years old (Source: Port and Harbor Bureau, Ministry of Land, Infrastructure, Transport and Tourism). On the other hand, the gap between supply and demand is widening as the divers responsible for underwater inspections are aging and there is a shortage of divers. Underwater inspection in shallow waters is dangerous work that involves multiple risks such as visibility, current, and residual pressure management, and the challenge was to create a sustainable inspection system that would keep costs down while ensuring safety.■ This demonstration result and technical featuresIn this demonstration, we succeeded in a series of operations in which the drone was flown automatically by remote control from land, dived in the target area, and inspected the breakwater while automatically navigating underwater.
The greatest feature of this project is that it has achieved remote automatic underwater navigation inspection at a low cost. Normally, automatic underwater navigation for purposes such as seabed resource exploration requires expensive devices such as INS (Inertial Navigation System) and DVL (Doppler Ground Speed ​​Meter). However, in this development, by adopting the ``high-precision acoustic positioning technology'' that KDDI Corporation has cultivated through the maintenance and inspection of submarine communication cables, we have achieved stable automatic underwater navigation without the use of these expensive devices. This makes it possible to use drones to replace inspection work that was previously performed by divers at a lower cost.■Experiment detailsDemonstration date: March 24, 2026
Demonstration location: Shizaki Port, Minamichita Town, Aichi Prefecture
Demonstration summary: At the breakwater off the coast of Shiozaki Port, we demonstrated whether automatic underwater navigation using acoustic positioning can efficiently photograph the underwater part of the breakwater without omissions, using the following procedure.
　　　　　1.Automatic flight and landing in the target area by aerial drone
2. Detachment of underwater drone and automatic diving underwater
3. Automatic navigation and photography of the underwater part of the breakwater along pre-set waypoints
4. Underwater drone recovery and return to land by automatic flight
Demonstration results: Using automatic underwater navigation using acoustic positioning technology, we were able to efficiently photograph the breakwater wall without being swept away by the current and without any omissions. This makes it possible to replace the underwater inspection work previously performed by divers at a lower cost.■ Future outlookThe three companies will continue to aim to realize a society where dangerous underwater work can be carried out more safely and at lower cost using underwater autonomous navigation technology of water-air hybrid drones. In the future, we will continue to work on technological development and demonstration experiments, not only for inspecting the underwater infrastructure of ports, but also for quickly understanding the underwater damage situation in the event of a disaster, and applying this technology to the fishing industry such as fixed nets and fish farms, with the aim of early practical application and social implementation.

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