A team of Rice University engineering students has developed a new way for underwater robots to move around, save power and work more efficiently and quietly.

The robot uses reversible hydrogen fuel cell-based buoyancy control devices that convert water into hydrogen and oxygen (and the reverse) using electricity. Traditional underwater robots use thrusters or large pumps and propellers to change and hold depth, which can be heavy, have higher costs and use more energy. The use of reversible hydrogen fuel cells with balloons, allows the new robot to smoothly adjust its depth with less energy usage, according to a statement from Rice.

The project was part of a year-long senior design capstone by six students, known as Team Bay-Max, in Rice's Oshman Engineering Design Kitchen.

The students—Andrew Bare, Spencer Darwall, Noah Elzner, Rafe Neathery, Ethan Peck and Dan Zislis— won second place in the Willy Revolution Award for Outstanding Innovation at the Huff OEDK Engineering Design Showcase held at the Ion last month.

“Having spent a year on it now and putting so much time into it, getting to see the result of all that work come together is really rewarding,” Peck said in the statement.

“With a project like this, integration was critical,” Zislis added. “Another takeaway for me is the importance of determining a clear scope for any given project. With this robot, we could have focused on a lot of different things. For instance, we could have worked on improving fuel cell efficiency or making a robotic arm. Instead, we chose to keep these other elements simple so as not to divert focus away from the main part, which is the buoyancy control device. This kind of decision-making process is not just part of good engineering, but it’s relevant with everything in life.”

Elzner, for instance, focused on the dashboard that the robot feeds information to as it collects data from different sensors. It displays core system information, real-time graphs of the robot’s location and a simulation of its relative orientation, according to the statement.

Darwall, took a " deep dive into control theory and learn(ed) new software" to incorporate the video game joystick that allows the robot to combine manual control with an automatic stabilizing algorithm.

The proof-of-concept robot has potential applications in environmental monitoring, oceanographic research, and military and industrial tasks, according to Rice.

The team based the project on an academic paper by Houston researchers that showed that fuel cell-enabled depth control could reduce autonomous underwater vehicles’ energy consumption by as much as 85 percent.

It was authored by Rice professor Fathi Ghorbel and members of the University of Houston's Zheng Chen lab.

“This collaborative research aims to develop tetherless continuum soft engines that utilize reversible proton exchange membrane fuel cells and water electrolyzers to drive volume-mass transformation," Ghorbel said in a statement. "Through this design project, the BayMax team proved the efficacy of this technology in AUV interaction with the physical world.”

Ghorbel, Rice mechanical engineering lecturer David Trevas, and Professor in the Practice, Electrical and Computer and Engineering Gary Woods mentored the team.