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

Ordinarily, underwater ROVs (remotely operated autos) and AUVs (autonomous underwater autos) 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 sometimes 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 gas cells. They built-in 4 of the gadgets into an ROV they constructed themselves, referred to as the Monarch.

Water-splitting gas 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, can even convert the 2 gases again into liquid. As a result of the gases have a decrease density than the liquid, they’ve a better quantity.

This phenomenon is exploited by the Monarch.

Jeff Fitlow/Rice College

If the ROV wants to extend its buoyancy, distilled liquid water in its gas cells is transformed into hydrogen and oxygen fuel, which inflate balloons positioned on prime of every cell. When the automobile 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 degree within the water, by mechanically 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 recent versus salt water, the system will be set to carry the automobile 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 gas 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 vitality consumption of AUVs by as much as 85% as in comparison with conventional thrusters.

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

Jeff Fitlow/Rice College

For sure, in real-world purposes, significantly stronger bladders may very well be utilized rather than the rubber balloons. The bottom know-how may conceivably additionally discover use in non-aquatic purposes reminiscent of 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 may see the Monarch in motion, within the video beneath.

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

Supply: Rice College