Robotic Fish Can Utilize Aquatic Environment 'Flowscape'

Lee Rannals for redOrbit.com – Your Universe Online

Researchers writing in the Proceedings of the Royal Society A say they have developed a new robotic fish that has lateral line sensing capabilities.

The FILOSE team members have spent four years investigating fish lateral line sensing, which is a sensing organ found in aquatic vertebrates used to detect movement and vibration in the surrounding water. This organ essentially helps a fish’s orientation in the water. The team set out to understanding how a fish detects and exploits flow features in water, and then use their findings to develop efficient underwater robots based on biological principles.

Flow can be measured and characterized on many salient features that do not change. This “flowscape” is a flow landscape that helps fish and robots orient themselves, navigate, and control their movements in water.

“So far, flow in robotics is treated as a disturbance that drives the robots away from their planned course,” says Prof. Maarja Kruusmaa, the Scientific Coordinator of the FILOSE project. “We have shown that flow is also a source of information that can be exploited to better control the vehicle. Also, flow can be a source of energy if we can understand the flow dynamics and interact with eddies and currents in a clever way.”

Experiments performed by the FILOSE team have demonstrated that a fish robot can save energy by finding favorable regions in the flow where the currents are weaker, or by interacting with the flow to help push the robot forward. The team’s robot is able to detect flow direction and swim upstream or hold station in the flow while compensating for the downstream drift by measuring flow speed.

“It is similar to reducing your effort in the tailwind of another cyclist or reducing the fuel consumption of your car by driving behind a truck,” Kruusmaa says.

FILOSE collaborator Prof. William Megill, who led the University of Bath’s contribution to the project, said their project has helped to contribute to the understanding of the “fish-centric” viewpoint of the aquatic environment.

“By recording flow sensor data from a robotic fish head which we’ve programmed to move like a real fish in similar flow conditions, we are able to understand what fish are able to perceive,” said Megill.

The researchers developed several prototype artificial lateral lines and robot actuators in the robot fish to investigate different aspects of sensing and locomotion in fluids.

Michigan State University scientists announced the development of a new robot fish called Grace, capable of traveling autonomously through the water. This fish is equipped with sensors that help it measure water temperature, quality and other pacts. Scientists could eventually use this fish to help provide valuable information to help clean up lakes and rivers.

“This is why we integrated both locomotion modes – gliding and swimming – in our robot,” said Xiaobo Tan, an MSU associate professor of electrical and computer engineering who designed and built Grace. “Such integration also allows the robot to adapt to different environments, from shallow streams to deep lakes, from calm ponds to rivers, with rapid currents.”

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