A diving robot to clean coastal areas

Tested this year in Venice, the Maelstrom project platform has a robot responsible for underwater waste recovery. Controlled by a cable system, it can operate at a maximum depth of twenty meters.

Despite its two tons, it dives in search of dirt under the water that it brings to the surface. He is the mobile part of a floating and robotized platform, dedicated to cleaning the seabed. Designed as part of the European Maelstrom project bringing together fourteen partners from eight countries, the set takes the form of a floating barge, hollowed out in its center to leave a pool-like space for robot that dives. A preliminary acoustic survey identifies a high concentration of waste and indicates the area to be cleaned.

The robot can go down to a depth of 15 or 20 meters and work on an area of ​​70 square meters.

SAccording to the Maelstrom team’s estimates, 83 million tons of plastic waste are polluting the oceans. Carrying his stone in the fight against this plague, thehe barge is a response more specifically suited to cleaning up coastal environments. Therefore the robot can go down to a depth of 15 or 20 meters and work in an area of ​​70 square meters without having to move the rest of the barge.

Eight cables for a maneuverable and precise robot

The diving robot is controlled by a system of eight cables, connected to four poles, its winding and unwinding offers surprising freedom and precision of movement. The robot is therefore able to handle heavier loads than if it were pushed like an ordinary underwater robot and ensures its stability in the presence of currents. The precision of this system also makes it possible to avoid a major difficulty: GPS does not work in water and therefore cannot indicate the position and orientation of an underwater robot.

The floating robotic platform of the Maelstrom project


Discover the first floating and robotic platform for cleaning the seabed, tested in Venice in September 2022.


Tecnalia 2022 / EU H2020 MAELSTROM Project

To our knowledge, this is an unprecedented mix between a cable robot and a remotely operated underwater vehicle, two main specialties of our laboratory.explains Marc Gouttefarde, CNRS research director at the Computing, Robotics and Microelectronics Laboratory of Montpellier (Lirmm). We worked on the controls and sensors of the robot, with a camera system and an acoustic sensor that measures the distance between the moving part of the platform and the seabed. An inertial unit also monitors the orientation of the robot when it is underwater. The rest of the engineering was carried out by the Tecnalia research foundation. »

First trials in turbulent waters

The platform was tested for two weeks, in September, in the lagoon of Venice under the coordination of the Italian laboratory CNR-ISMAR. The robot is equipped with a vacuum cleaner and a grapple to catch waste such as plastic, tires or fishing nets. ” We encountered difficulties at this stage of the experiment, because, if the weather was very good outside the water, the visibility under the water was almost non-existent.illustrated by Marc Gouttefarde. You can’t identify trash until you’re a few centimeters away from them.. »

First tests in the Venice lagoon in September 2022.

In response, Lirmm plans to carry out work near Montpellier, where the clarity of the water should make it possible to establish a solid database of photographs and videos of underwater debris. ” We have done similar work on identifying fish“, refers to the researcher. The database will make it possible to train artificial intelligences so that they themselves assign to the robot the garbage to remove. The researchers are also working on the automatic recovery of garbage, that is, the possibility for a person operator to click on the trash he identified in a video for the system to retrieve it.

The robot climbed onto the wheel chosen by the grapple.

Other ways for improvement are also being followed. ” Cable robot systems can easily be scaled up to treat a larger area, but they are expensiveregrets Marc Gouttefarde. Another idea, the barge is currently towed by a boat, but we can totally imagine a motorized version equipped with surface GPS to take it to clean specific areas. »

Lthe barge is currently being towed by a boat, but we could very well imagine a motorized version equipped with surface GPS to take it to clean up specific areas.

The barge was also designed with the help of Servizi Tecnici, a Venetian company specializing in the construction of floating surfaces for events, for example for fireworks or concerts. The Maelstrom team is considering dismantling the system to test it under different conditions, but new locations have yet to be chosen. The Maelstrom project also has another component: a bubble barrier system tested on the Ave River in Portugal. This prevents trash from continuing to go into the ocean and pushes it to the banks where it can be collected more easily. All without disturbing aquatic life.

While waiting for new full-scale experiments, Lirmm researchers continue to work on the artificial intelligence part of the project. Automatic detection and retrieval of litter will really speed up the cleanup of coastal areas.

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