Development of a portable monitoring sensor for the prevention of underwater robot collision accidents

On March 13, NEC announced that it has developed a small, portable underwater monitoring sensor capable of detecting objects approaching underwater and has successfully completed real-world environment demonstrations at a port in Nagasaki Prefecture. The company plans to proceed with development toward commercialization, with the start of service scheduled within fiscal year 2027.

The use of underwater vehicles such as underwater robots is expanding, increasing the risk of contact with vessels and accidents occurring at coastal facilities. Since detecting problems occurring underwater is more difficult than on the sea surface or on land, delays in discovery and response can lead to serious accidents. Therefore, early identification of the situation and response are essential.

The developed sensor monitors the underwater surroundings of critical infrastructure, such as ports and power facilities, as well as vessels and offshore facilities that are not equipped with sonar. It quickly detects approaching underwater objects, such as divers or underwater robots, and notifies operators by displaying them on a monitor.

It was developed using the underwater acoustic technology that the company has cultivated for more than 90 years. Until now, the company has provided underwater monitoring sensors for sea bottom installation.

However, there were challenges such as the high hurdle for introduction due to large-scale installation work on the seabed and operational constraints like securing installation space. In response, the underwater sensor has now been downsized to approximately one-tenth the volume of previous models, making it a portable size.

Additionally, the operation unit, which previously consisted of multiple devices, has been modularized into components, significantly reducing the volume of the operation and display equipment and making it possible to install on vessels.

In general, underwater sound wave detection is difficult in environments with a lot of ambient noise, such as shipping lanes and coastal areas. In particular, the shallow water depths in bays and harbors and their proximity to economic activity zones create an environment where sound waves of various frequencies are mixed together, requiring advanced signal processing techniques to extract the desired acoustic signals.

The new sensor uses signal processing technology that the company has cultivated over many years of sonar development. It is capable of accurately extracting the desired signal even from complex environmental sounds and has a high detection capability. In addition, it is portable and can be operated in a variety of situations. For example, it can be installed on board a vessel and used as a simple vessel sonar to monitor the position of divers during stop work or to detect underwater vessels approaching the vessel.

Vessels conducting marine research or underwater work often do not carry sonar for horizontal detection. Thus, this sensor is also effective for ensuring the safety of such vessels. Moreover, the sensor allows for remote operation via the internet, making it usable in environments where it is difficult for operators to be permanently stationed, such as offshore wind power facilities or remote islands. It is also expected to have a labor-saving effect on facility monitoring. In addition, it can respond to diverse needs, such as underwater monitoring for offshore oil drilling facilities, fixed nets, and fishing grounds.

In February of this year, the company conducted a real-world demonstration using this sensor at a port in Nagasaki Prefecture and succeeded in detecting divers and underwater vehicles from several hundred meters away. The sensor was also exhibited and introduced at the "WIND EXPO: Int'l Wind Energy Expo" held at Tokyo Big Sight from March 17 to 19.