Marine litter-detecting robots with underwater capability developed by Nagasaki Univ. team

NAGASAKI -- A Nagasaki University team has developed camera-equipped robots that can ascertain the state of marine litter on and under the water -- technology they hope will pave the way to automatic collection of such garbage in the future.

The team, led by the university's Vice President Ikuo Yamamoto, a professor of robotics, aims to produce working models that can be put to use next autumn.

The impact of marine debris on the ecosystem is becoming serious. The problem is expanding on a global scale, and according to one estimate, the weight of plastic waste in oceans will top that of all fish by 2050.

The team has conducted research in the waters around Tsushima Island off mainland Nagasaki Prefecture in the Sea of Japan, where as much as 20,000 cubic meters of garbage from Japan and overseas is said to be washed ashore annually.

To date, washed-up waste has been surveyed by human sight and with drones, but with these methods, the situation in the water and on the seabed could not be assessed. Yamamoto has accordingly been developing robots with graduate students since the spring of 2020 in cooperation with the Tsushima Municipal Government and marine conservation groups, among other bodies.

The main robot -- called the autonomous surface vehicle -- is roughly 1.4 meters long, 1.1 meters wide, and weighs about 30 kilograms. It is equipped with an above-water camera that can take images automatically while rotating 360 degrees. Accompanying it is a smaller underwater robot -- or remotely operated vehicle -- that has another camera. Photos and videos are sent to the ground in real time, making it possible to accurately grasp information including the amount, location and types of debris.

The underwater robot observes the location and amount of litter while moving freely in the water apart from the surface vehicle. It is apparently possible to anticipate the direction in which the debris will flow by analyzing the data gathered by the main robot and data from ocean current simulations.

The researchers started testing the robots off Tsushima Island in October, and succeeded on Nov. 28 in creating a 3D model of an expansive body of water and the seabed based on the data collected by the remotely operated robot. This enabled them to foresee spots where debris was likely to accumulate.

A robot to automatically collect marine garbage is also under development. The team hopes to apply the technology in the future to find and remove plastic waste from the sea, as well as harmful plankton responsible for red tide.

Yamamoto said eagerly, "These marine debris robots can accurately capture images of the amount and location of waste even along an intricate coastline that is difficult for humans to approach. With cooperation between the government, industry and academia, we'd like to show the world the effectiveness of these robots and popularize them."

(Japanese original by Atsuki Nakayama, Nagasaki Bureau)