Artificial tuna fin to accelerate underwater drones
Underwater drones usually use electric motor propeller drives. Researchers now want to eliminate their disadvantages with an artificial fish fin.
The artificial fish fin contains chambers that can be filled with compressed air and thus influence the dynamics of the fin.
(Image: Shirah Abrishamian)
A research team at the University of Maryland is working on improving quiet and efficient propulsion systems for underwater drones. A dedicated unmanned underwater drone is currently under development. To this end, the researchers have developed an artificial tail fin based on that of a tuna. The streamlined fin is designed to make the underwater robot quieter, faster and more maneuverable.
Underwater drones are used for research in the sea, inspecting underwater cables and military tasks. The focus here is on ensuring that they move as quietly as possible and have efficient drives to save electricity. The thrusters commonly used to date are large and protrude from the sides of an underwater drone. This increases the resistance and requires more power during operation. They also have a larger design and have to maintain greater distances from obstacles in the water. Then there is the noise of the electric motors. They are not very suitable for research tasks in the sea, as the noise disturbs wildlife. Noise is also a hindrance for military use, as the camouflage of such underwater robots is then blown too quickly.
Artificial fish fin as propulsion
A fin that imitates the tail fin of a tuna should eliminate all existing problems with the propulsion of underwater drones, is the idea of Cecilia Huertas-Cerdeira, lead author of the study “A 3-DOF caudal fin for precise maneuvering of thunniform-inspired unmanned underwater vehicles”, which was published in Scientific Report. Huertas-Cerdeira analyzed what makes fish such good swimmers. Fish change the stiffness of their fins depending on the situation as they swim through the water, thus reacting to the forces of the flowing water. To prevent the fin from fluttering, for example, they stiffen certain areas of the fin, while making other regions more flexible.
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The initial result is a prototype from the 3D printer that mimics the behavior of a biological fish fin. It consists of a soft material with air-filled chambers in specific areas. The chambers are filled or emptied using compressed air, depending on how hard or soft the fin should be at the respective point. The aim is to imitate the dynamics of a biological fish's fin.
Huerta-Cerdeira hopes that the study will not only be used for his own underwater drone project, but will also inspire other scientists to develop alternative propulsion systems.
(olb)
