With the aim of tackling the climate change issue, University of California, San Diego engineering students in the Yonder Deep student organization are designing and 3D printing a low-cost, modular, and fully autonomous underwater vehicle (AUV) with the goal of enabling researchers to collect oceanographic and climate data.
The Yonder Deep team, now in its fifth year, installed in its torpedo-like AUV, an entire suite of sensors — temperature, pressure, hydrophones — versatile enough to withstand the frigid Arctic waters as well as the coastal waters of Southern California.
One of the team’s first missions is working to help quantify glacier melt and subsequent sea level rise. Such arctic research instruments already exist but getting them close to glacier terminuses can be challenging due to the dangerous nature of glacier research.
AUVs are a great solution, but even entry-level AUVs can cost upwards of $300,000. The Yonder Deep team sought to address this, and, over the past five years, has been developing its low-cost AUV using 3D printing.
The team’s AUV uses hydrophones to measure the rate of ice melting: As the ice melts, air is trapped inside the ice as bubbles escape, making a crackling noise. By monitoring the rate of these crackling noises, one can identify how fast the ice is melting.
Yonder Deep’s technical advisor and former President Daniel Ju and current President Satchel Birch said operating the AUV in the chilly Arctic conditions presents myriad challenges, including how the porous material’s water absorption would influence the object’s weight and buoyancy. Also, they had to study the durability, behavior, and geometry of the 3D-printed material and determine whether it could withstand the severe conditions.
The team has loftier goals, though.
“As engineers, it’s also important to think how we can use our unique skills to help tackle a problem that is usually approached as a social issue,” said Ju. “Climate change is an incredibly pressing global issue, and this project provides students with an opportunity to leave a large impact on the world while simultaneously developing important engineering skills.”
“Being able to study climate change, but also work to increase access to quality oceanographic research for the future, is what I think makes our mission so exciting,” said Birch. “On top of that, doing this as a team of only undergrads is a great opportunity to learn and teach together. One of my best memories was conducting these buoyancy calculations and seeing them work as a team during salt-water pool tests at Scripps.”
Ju said eschewing conventional manufacturing methods for 3D printing is “what makes this project so fun because no one has done this type of work at this scale before.”
“3D printing is normally used for prototyping, but our unique designs and processes enable the use of more additive manufacturing, which are the main reasons why Yonder Deep’s strategy is so versatile and affordable,” he added.
Yonder Deep is currently on its fourth full-scale prototype and anticipates that the current AUV will be ready for intensive testing by the end of the summer. If the testing goals are met by that point, physical oceanographer and team mentor, Grant Deane plans to use the AUV for his research trip to the Arctic.
“The Yonder Deep team is pushing the frontier of low-cost, high-value marine platforms for research in high-risk polar regions,” said Deane. “This kind of work is critical to understanding sea-level rise and developing systems for monitoring the Greenland ice sheet. It’s exciting to be working with this dynamic, motivated, and talented team of engineers to achieve these goals.”
Here is a Tech Briefs interview with Birch and Ju, edited for content and clarity.
Tech Briefs: The team is on its fourth full-scale prototype. How long does it take to fully 3D print an AUV?
Birch: Print time depends largely on the specs of the 3D printer you use and your model settings. We print our AUV parts on a Raise3D Pro2 + machine at relatively low speeds to get the highest quality possible out of our prints, and we print them at 100 percent infill. Normally, this level of infill is unnecessary for 3D-printed parts, but for us, vehicle buoyancy is one of our biggest concerns, so more infill lets us weigh our AUV down to control our buoyancy better.
All of that said, with our current process and infill percentage, it would take roughly two weeks to print the entire AUV with one printer, assuming you are able to start the next print as soon as the previous print finishes.
Ju: It also really depends on what we change between different AUV iterations. One of the huge benefits of our design is that it’s incredibly modular, so we can pick and choose what parts to replace/improve. This is also why 3D printing is a huge benefit because we have incredibly fast manufacturing turnaround times, allowing us to test new ideas quickly and cheaply.
Tech Briefs: How did you overcome the technical challenges you faced?
Birch: One of the difficult parts about planning for an arctic mission is that it’s almost impossible to test in arctic-like conditions before you get there. We have done a lot of research into plastic filaments and a lot of analysis with software tools to simulate what our AUV might experience, but at the end of the day they are estimates. We have had the best results by testing our AUV in water as much as possible, analyzing why certain parts failed or malfunctioned, and going back and doing it again. If our AUV can avoid any large-scale collisions, then our 3D-printed parts, according to our structural analysis should be fine, especially considering that we are printing them at considerably higher densities.
Tech Briefs: Can you explain in simple terms how the hydrophones work?
Birch: Hydrophones work similar to microphones, in that they measure acoustics through pressure variations in a fluid — in this case, water. One hydrophone can listen passively underwater and is very sensitive to noise; however, multiple hydrophones used in arrays can let you determine the direction of incoming sound and the position of the source. Our advisor, Dr. Grant Deane, has used hydrophones extensively to study the sounds that make air bubbles pop, and we plan to use four hydrophones arranged in a tetrahedron configuration to gather similar data at a glacier terminus in Svalbard, Norway.
Tech Briefs: Have there been any updates on the testing goals? Any concrete plans yet for a next step?
Birch: We recently had a full-scale AUV test at the end of February at a saltwater testing pool down at Scripps Institute of Oceanography. We were able to successfully test manual and autonomous diving, as well as run an abbreviated version of the autonomous routine we hope to use in the Arctic. This is a huge step forward for our current AUV prototype, but there is still a lot more testing we need to do. We have an idea for how our system behaves underwater, and we now need to fine-tune our control so that the data we collect is as accurate as possible.
We plan to have a few more pool tests in the next month or two, and hopefully conduct an open ocean test off the coast of Scripps Pier in the near future. If these tests go well and we can prove that our AUV is robust enough, sending it up to the Arctic is the next step.
Tech Briefs: What does the team aim to have the AUV cost?
Ju: Our AUV will end up costing around $3,000, depending on its sensor package (this only covers material and instrumentation costs). We are able to get the price down this low because of our material choices, manufacturing processes, and unique designs.
At the end of the day, our main goal is to create an affordable method of data collection and get it into the hands of people who are passionate about changing the world. Our team comprises hard-working and passionate engineers who want to see big changes in the world, so our work is purely non-profit and everything we do is for this mission.
Tech Briefs: Do you have any advice for engineers aiming to bring their ideas to fruition?
Birch: My one piece of advice for engineers, but also anyone who is trying to create something new, would be to understand that failure is necessary. When something doesn’t work, it is so easy to get caught in a cycle of feeling that you could have designed better, prepared more, or tested differently, but good design and good engineering is born out of a series of unique failures. They are the most direct feedback about the limits of your design, and it’s up to you to push those limits.
Ju: My advice for young engineers (and even for working professionals) is to keep an open mind. There are no stupid ideas; be creative, because anything and everything can lead to a possible solution. You never know where, who, or what you may find inspiration from!
Along the same line of advice, absorb everything around you — like a sponge. The more things you expose yourself to, the more knowledgeable and open-minded you become. The fun part here is that there is more information in the world than any one person could ever hope to learn, so the learning never really ends.
Tech Briefs: Anything else you’d like to add?
Ju: Special thanks to our sponsors from Raise3D and the Green Initiative Fund for making this work possible, and thank you to the general public! We’ve received so much positive feedback from everyone, and it has been great to see people voicing their support for our mission.