Flying Fish Robot Has Unique “Engine”
Jeffrey Heimgartner posted on September 23, 2019 |

Robotics have become a useful tool for environmental monitoring, both in water and on land. A robot that can do both presents some unique challenges, especially when it comes to powering it, but researchers from Imperial College London and the Swiss Federal Laboratories for Materials Science and Technology have overcome them with a new sea-to-land glider.

The palm-sized, bio-inspired robot works similarly to a flying fish. To make the transition from water to land, it uses a chemical reaction instead of an engine to propel itself.

“It doesn’t need any pistons or valves, which are typical for combustion processes or internal combustion engines,” said Mirko Kovac, director of the Aerial Robotics Laboratory at Imperial College London. “It uses the property of the fluid, the gas, the water, and this reaction to create the various stages of the combustion.”

A) Proposed mission stages showcasing the transition from a floating state to an airborne jetting phase and back to floating. (B) 3D model render of the underside of the robot highlighting its key features. (C) Section of fuel container, with fuel for one mission cycle, showing a water drop about to react with the calcium carbide. (Image courtesy of Imperial College London.)
A) Proposed mission stages showcasing the transition from a floating state to an airborne jetting phase and back to floating. (B) 3D model render of the underside of the robot highlighting its key features. (C) Section of fuel container, with fuel for one mission cycle, showing a water drop about to react with the calcium carbide. (Image courtesy of Imperial College London.)

The robot’s “engine” works by pumping water through a master chamber that is siphoned into a smaller chamber with calcium carbide powder, forming acetylene gas. The gas is forced into the main chamber and ignited, making the robot airborne. The robot glides through the air for approximately 26 meters. Each jump it makes requires only .2 grams of calcium carbide and a minimal amount of water. The glider currently stores enough calcium carbide to complete about 20 jumps and uses the water from which it is submerged.

“Since the chamber fills passively and the environmental water acts as a piston, we can create a full combustion cycle with only one moving part, which is the pump that mixes the water with the fuel,” Kovac said. “It doesn’t need to carry a lot. This size is good because it’s very portable, it’s disposable, and it’s inexpensive.”

This illustration shows the combustion inside the robot propelling it out of the water. (Image courtesy of Imperial College London.)
This illustration shows the combustion inside the robot propelling it out of the water. (Image courtesy of Imperial College London.)

Testing has been conducted at multiple water sites, including a lake and wave tank. These tests proved successful, including in rough water conditions. The powerful “engine” generates a force 25 times the robot’s weight. Since it has the potential to make multiple jumps and float, it could prove beneficial in taking multiple samples.

“These kinds of low-power, tether-free robots could be really useful in environments that are normally time- and resource-intensive to monitor, including after disasters such as floods or nuclear accidents,” said Raphael Zufferey, lead author of the paper.

The team isn’t done with its new robot just yet. The researchers have plans to create larger robots and are testing new materials for field trials around coral reefs and offshore energy platforms.

Interested in more nature-inspired robotics? Check out A Lesson from Reptiles: How a Snake’s Motion Can Inspire Better Robots and SlothBot Provides Slow, Steady Environmental Monitoring.


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