Power-efficient underwater robotic rises and falls through fuel-cell balloons


If scuba divers use inflatable BCDs (buoyancy management gadgets), why do not underwater robots? Nicely, an experimental new one does, and the know-how is claimed to be way more energy-efficient than conventional strategies of shifting up and down within the water.

Ordinarily, underwater ROVs (remotely operated automobiles) and AUVs (autonomous underwater automobiles) are designed to be neutrally buoyant. This implies they neither sink to the underside nor float to the floor when underwater.

To be able to transfer vertically within the water column, they usually use their highly effective electrical thrusters. Using an electrical pump to attract water out and in of onboard ballast tanks is another choice. In both case, a substantial quantity of battery energy is expended within the course of.

Searching for a extra environment friendly various, Rice College’s BayMax crew of engineering college students regarded to reversible water-splitting gasoline cells. They built-in 4 of the gadgets into an ROV they constructed themselves, referred to as the Monarch.

Water-splitting gasoline cells make the most of the electrolysis course of to separate liquid water into its two elements, hydrogen and oxygen fuel. Reversible cells, as their identify implies, may convert the 2 gases again into liquid. As a result of the gases have a decrease density than the liquid, they’ve a larger quantity.

This phenomenon is exploited by the Monarch.

The Monarch ROV in a pool test
The Monarch ROV in a pool take a look at

Jeff Fitlow/Rice College

If the ROV wants to extend its buoyancy, distilled liquid water in its gasoline cells is transformed into hydrogen and oxygen fuel, which inflate balloons situated on prime of every cell. When the car must lower buoyancy, these gases are transformed again to liquid, inflicting the balloons to deflate.

The know-how can moreover be utilized to maintain the vessel sitting horizontally stage within the water, by routinely activating particular person cells as wanted. What’s extra, as a result of the buoyancy of even “neutrally” buoyant ROVs and AUVs adjustments at totally different depths, or in contemporary versus salt water, the system will be set to carry the car at any given depth.

Whereas the electrolysis course of does use some electrical energy, it wants significantly lower than can be required to rise or fall using thrusters. Electrical energy produced by the gasoline cells may even be used to assist energy the ROV.

In actual fact, in a 2023 paper that impressed the BayMax crew to create the Monarch, scientists from Rice College and the College of Houston acknowledged that fuel-cell-enabled depth management may scale back the power consumption of AUVs by as much as 85% as in comparison with conventional thrusters.

And what’s extra, the gasoline cells are claimed to be lighter and cheaper than vertical thrusters. They’re additionally far quieter, in order that they’re much less more likely to startle underwater wildlife.

From left, BayMax team members Noah Elzner, Dan Zislis, Ethan Peck, Spencer Darwall, Andrew Bare and Rafe Neathery
From left, BayMax crew members Noah Elzner, Dan Zislis, Ethan Peck, Spencer Darwall, Andrew Naked and Rafe Neathery

Jeff Fitlow/Rice College

Evidently, in real-world purposes, significantly stronger bladders could possibly be utilized instead of the rubber balloons. The bottom know-how may conceivably additionally discover use in non-aquatic purposes similar to assistive wearable gadgets or robotic clothes.

“The cool factor about this for us is that it’s a know-how that’s actually innovative, it’s one thing that hasn’t been accomplished earlier than precisely the best way we’re doing it,” says BayMax member Andrew Naked. “We’re the primary ones to implement this know-how in a tool with pitch roll and in depth controls, so we’re actually enthusiastic about that.”

You’ll be able to see the Monarch in motion, within the video under.

The challenge is a part of a collaborative challenge between the labs of Rice College’s professors Fathi Ghorbel and Laura Schaefer, and the College of Houston’s Prof. Zheng Chen.

Underwater robotic pioneers new energy-efficient buoyancy management

Supply: Rice University



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