Bio-inspired bot

"Flying fish" robot can dive and fly

Sep 12, 2019 | HAYLEY DUNNING

A bio-inspired bot uses water from the environment to create a propelling gas and launch itself from the water’s surface. The robot had been developed by researchers at Imperial College London. It can travel 26 meters through the air after take-off and could be used to collect water samples in hazardous and cluttered environments, such as during flooding or when monitoring ocean pollution, report the team lead by Mirko Kovac, who also heads the joint "Materials and Technology Center of Robotics" at Empa, in the latest issue of "Science Robotics".

Image: Aerial Robotics Lab/Imperial College London

Robots that can transition from water to air are desirable in certain situations, but the launch requires a lot of power, which has been difficult to achieve in small robots. Now, researchers at Imperial College London have invented a system that requires just 0.2 grams of calcium carbide powder in a combustion chamber. The only moving part is a small pump that brings in water from the environment the robot is sat in, such as a lake or ocean.

The water is then combined with the calcium-carbide powder in a reaction chamber, producing a burnable acetylene gas. As the gas ignites and expands, it pushes the water out as a jet propelling the robot clear of the water and into a glide of up to 26 meters.

“Water-to-air transition is a power-intensive process, which is difficult to achieve on a small-scale flying vehicle that needs to be lightweight for flight", explains Mirko Kovac, Director of the "Aerial Robotics Laboratory" at Imperial and the joint "Materials and Technology Center of Robotics" at Empa. “We have used water-reactive chemicals to reduce the materials that the robot needs to carry. 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.”

Image: Aerial Robotics Lab/Imperial College London
A lot of thrust

The team tested the robot in the lab, in a lake, and in a wave tank, showing that it can escape from the water’s surface even under rather rough conditions. While similar robots often require calm conditions to leap from the water, the team’s invention generates a force 25 times the robot’s weight, giving it a greater chance of overcoming the waves.

The robot, which weighs just 160 grams, can "jump" multiple times after refilling its water tank. This could allow it to float on water and take samples at multiple points without additional power, saving energy over longer distances compared to an electrically powered robot.

The Imperial team is now working with researchers at Empa to build new vehicles using advanced materials and begin field trials of the robot in a range of environments, including monitoring the oceans around coral reefs and offshore energy platforms.

Raphael Zufferey, first author on the paper said: “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.”

The tests were carried out in the Brahmal Vasudevan Multi-terrain Robotics Arena, which was founded on a philanthropic gift from Brahmal Vasudevan.


Further information
Dr. Mirko Kovac
Empa, Materials and Technology Center of Robotics
Phone +41 58 765 46 89

Editor / Media contact

Hayley Dunning
Research Media Manager (Natural Sciences)
Phone +44(0)20 7594 2412
Out of hours duty media officer: +44 (0)7803 886 248

Dr. Michael Hagmann
Empa, Communications
Phone +41 58 765 45 92


R Zufferey, A Ortega Ancel, A Farinha, R Siddall, SF Armanini, M Nasr, RV Brahmal, G Kennedy, M Kovac; Consecutive aquatic jump-gliding with a water-reactive fuel; Science Robotics; doi: 10.1126/scirobotics.aax7330

Images and video of the robot can be downloaded here.
The video can also be embedded from here.
All images and video credit: Aerial Robotics Lab/Imperial College London

About Imperial College London
Imperial College London is one of the world’s leading universities. The College’s 17,000 students and 8,000 staff are expanding the frontiers of knowledge in science, medicine, engineering and business, and translating their discoveries into benefits for our society. Imperial is the UK’s most international university, according to Times Higher Education, with academic ties to more than 150 countries. Reuters named the College as the UK’s most innovative university because of its exceptional entrepreneurial culture and ties to industry. More information.

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