Imagine deploying a swarm of robots that can clean up contaminated water systems or survey remote ocean locations without worrying about battery life.
This may be the future of the Row-bot project. The Row-bot is an autonomous swimming robot capable of operating indefinitely by scavenging energy from its environment.
Currently, the Row-bot is still in the prototyping stage at the University of Bristol. The robot moves across the surface of the water by mimicking the rowing motion of the water boatman insect. Two subsystems power the Row-bot.
Notonecta glauca, commonly known as a water boatman. (Image courtesy of Paul Albertalla/Wikimedia Commons.)
The first is a bio-inspired energy source which generates power through a microbial fuel cell (MFC) “stomach.” The second system is a bio-inspired actuation that starts the refuelling process. This actuation system also moves the robot, with an energy requirement that is less than what the first system generates.
The energy generation process is achieved by feeding on the chemical energy generated by the microbial fuel cell.
Generally, MFCs work by using or mimicking bacterial respiration found in nature. Essentially, MFCs use microorganisms as the ‘catalysts’ to convert chemical energy into electrical energy. These systems typically have anode and cathode compartments separated by a cation specific membrane.
Fuel is oxidized by the microorganisms in the anode compartment, which generates CO2, electrons and hydrogen ions. An external electric circuit transfers the electrons to the cathode compartment, and the ions are transferred to the cathode through the membrane, completing the circuit. The electrons and ions then combine with oxygen in the cathode to form water.
In the case of the Row-bot, the MFC’s processing of the organic material in the water is what generates the electrical current.
When in need of energy, the Row-bot opens its soft robotic mouth and rows forward to fill the MFC stomach with nutrient-rich dirty water. It then closes its mouth, and the MFC digests these nutrients.
Inspired by the water boatman’s beak-like mouth, the actuated orifice at either end of the MFC opens and closes through the bending of a flexible acetate envelope structure.
Once its electrical energy stores are recharged, the Row-bot will move off to a new location.
“The work shows a crucial step in the development of autonomous robots capable of long-term self-power. Most robots require re-charging or refuelling, often requiring human involvement,” said Jonathon Rossiter, professor of robotics at the University of Bristol where the Row-bot project originates.
The team sees future applications like environmental clean-up, as described by PhD student Hemma Philamore. “We anticipate that the Row-bot will be used in environmental clean-up operations of contaminants, such as oil spills and harmful algal blooms, and in long term autonomous environmental monitoring of hazardous environments, for example those hit by natural and man-made disasters.”
The technology of the Row-bot is still in the early stages of development. Certainly there will need to be more work and greater refinement of the concept before any viable commercial production.
There is also a potential concern regarding the by-products of the MFC engine, specifically the creation of CO2. Depending on the amount of CO2 created and emitted by these devices, it could be hard to justify cleanup of one environmental pollutant if it means creating more green-house gas.
Especially with oil spill cleanup, it may be more advantageous to design a bot that will use some contaminant oil to power itself, but collect the rest to return to land where the oil can be re-refined and used.
The team will present their paper, “Row-bot: An energetically autonomous artificial water boatman” at the 2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) congress.