Robotics has advanced in leaps and bounds over the past few decades, but in terms of decentralized coordination in robot swarms, they far behind biological swarms. Researchers from Harvard University’s Weiss Institute are working to close the gap, and have developed Blueswarm, a school of robotic fish that can exhibit swarm behavior without external centralized control.
In real fish schools, the movement of an individual fish depends on those around it. To allow each robotic fish to estimate the position of its neighbors, they are equipped with a set of 3 blue LEDs, and a camera on each side of the body. Four oscillating fins, inspired by reef fish, provide 3D control. The actuator for the fins is simply a pivoting magnet inside a coil being fed an alternating current. The onboard computer of each fish is a Raspberry Pi W, and the cameras are Raspberry Pi Camera modules with wide-angle lenses. Using the position information calculated from the cameras, the school can coordinate its movements to spread out, group together, swim in a circle, or find an object and then converge on it. The full academic article is available for free if you are interested in the details.
Communication with light is dependent on the clarity of the medium it’s traveling through, in this case, water — and conditions can quickly become a limiting factor. Submarines have faced the same challenge for a long time. Two current alternative solutions are ELF radio and sound, which are both covered in [Lewin Day]’s excellent article on underwater communications.
Underwater exploration and research can be exceedingly dangerous, which is why remotely operated vehicles (ROVs) are so commonly used. Operators can remotely command these small submersibles to capture images or collect samples at depths which would otherwise be unreachable. Unfortunately, such technology comes at a considerable price.
Believing that the high cost of commercial ROVs is a hindrance to aquatic conservation efforts, [Noeël Moeskops] has been developing an open source modular ROV he calls Aruna. Constructed largely from off-the-shelf components and 3D-printed parts, the Aruna promises to be far more affordable than anything currently on the market. Hopefully cheap enough to allow local governments and even citizens to conduct their own underwater research and observations.
More than just the ROV itself, Aruna represents an entire system for developing modular underwater vehicles. Whether you decide to build the boilerplate ROV documented and tested by [Noeël], or implement individual components into your own design, the project is a valuable source of hardware and software information for anyone interested in DIY underwater robotics.
The Earth’s oceans are a vast frontier that brims with possibilities for the future of medicine, ocean conservation, and food production. They remain largely unexplored because of the physical limits of scuba diving. Humans can only dive for a few hours each day, and every minute spent breathing compressed air at depth must be paid for with a slower ascent to the surface. Otherwise, divers could develop decompression sickness from nitrogen expanding in the bloodstream.
Cousteau’s first sea lab, Conshelf 1 (Continental Shelf Station) held two people and was stationed 33 feet deep off the coast of Marseilles, France. Conshelf 2 sheltered six people and spent a total of six weeks under the Red Sea at two different depths.
Conshelf 3 was Cousteau’s most ambitious habitat design, because it was nearly self-sufficient compared to the first two. It accommodated six divers for three weeks at a time and sat 336 feet deep off the coast of France, near Nice. Conshelf 3 was built in partnership with a French petrochemical company to study the viability of stationing humans for underwater oil drilling (before we had robots for that), and included a mock oil rig on the nearby ocean floor for exercises.
Several underwater habitats have come and gone in the years since the Conshelf series, but each has been built for a specific research project or group of tasks. There’s never really been a permanent habitat established for general research into the biochemistry of the ocean.
In Subnautica, players explore an alien underwater landscape with the help of a number of futuristic tools and vehicles. [Robert Cook] found himself particularly enamored with the large submarine you unlock towards the later parts of the game, so much so that he decided to build his own real-life version.
Even though the RC version of the Cyclops [Robert] has designed is only big enough to explore swimming pool sized alien landscapes, it’s by no means a simple build. In fact, the sub’s internal watertight compartment holds an impressive array of electronics and systems that are arguably overkill for what’s essentially a toy. Not that we’re complaining, of course.
Beyond the electronics and a few key components, almost every part of the RC Cyclops has been 3D printed. From the bulkheads that cap off the internal watertight acrylic tube to the hull itself, there’s a lot of plastic aboard this ship. Which might explain why it takes nearly two kilograms of lead weight to get the sub close to neutral buoyancy. From there, a clever ballast tank arrangement made from a syringe and peristaltic pump allow the vehicle to dive and surface on command.
[Robert] is in the process of releasing the STL files for all the submarine’s 3D printed components, and has done an excellent job of documenting the roughly four months he’s spent working on the project in a series of videos on his YouTube channel. The videos contain a wealth of fascinating tips and tricks regarding DIY submersible vehicles, such as selecting the proper radio frequencies for maximum penetration through water and counteracting the permeability of 3D printed parts with a generous coating of epoxy.
When you think of robots that were modeled after animals, a brittle star is probably not the first species that comes to mind. Still, this is the animal that inspired [Zach J. Patterson] and his research colleagues from Carnegie Mellon University for their underwater crawling robot PATRICK.
PATRICK is a soft robot made from molded silicone. Each of his five limbs contains several shape memory alloy (SMA) springs which can be contracted through Joule heating thereby causing the limbs to bend. The robot’s control board is sending and receiving commands via Bluetooth Low Energy from a nearby computer. To control PATRICK’s motion the researchers constructed a closed-loop system where an offboard OpenCV based camera system is constantly tracking the robot. As shown in the video below with an average velocity of 1 cm/s, PATRICK’s movement is a bit sluggish but the system is supposedly very robust against uncertainties in the environment.
In the future [Zach J. Patterson et al.] would like to improve their design by giving the robot the ability to grasp objects. Ultimately, also the offboard camera should be replaced with onboard sensors so that PATRICK can navigate autonomously.
We can’t tell if the Eelume actually exists, or if it’s just a good CG and a design concept, but when we saw the video below, we wanted to start working on our version of it immediately. What’s an Eelume? A robotic eel that lives permanently under the ocean.
If you have to take care of something underwater — like a pipeline — this could be much more cost-effective than sending divers to the ocean floor. We liked the natural motion and we really liked the way the unit could switch batteries and tool heads.
We do have some questions, though. How do you get rid of one battery and pick up another? There would have to be some battery capacity that doesn’t exchange, but that’s not very efficient since the new battery would have to recharge the internal battery. Perhaps you can add batteries at either end. Some of the still pictures don’t clearly show how the batteries fit in, although they do show the flexible joints, sensors, cameras, and thrusters, which are all modular.
According to the web site, tools can go on either end and there’s a robot arm. The device can apparently shape itself like a U to bring both ends to bear on the same area. Generally, we like robots that mimic nature, but this is one of the best examples of that being practical we’ve seen.
There’s a video on the site of what appears to be real hardware tethered in a swimming pool, though we couldn’t tell how much of the device was subject to remote control and how much would be autonomous. Communicating underwater is finicky and usually requires either an antenna on the surface or a very low frequency (and, thus, not much bandwidth). While completely duplicating this would probably be a feat, it might inspire some hacker-friendly eels.
We often think of submarines as fairly complex pieces of machinery, and for good reason. Keeping the electronics watertight can naturally be quite difficult, and maintaining neutral buoyancy while traveling underwater is a considerable engineering challenge. But it turns out that if you’re willing to skip out on those fairly key elements of submarine design, the whole thing suddenly becomes a lot easier. Big surprise, right?
That’s precisely how [Peter Sripol] approached his latest project, which he’s claiming is the world’s smallest remote control submarine. We’re not qualified to say if that’s true or not, but we were certainly interested in seeing how he built the diminutive submersible. Thanks to the fact that it started life as one of those cheap infrared helicopters, it’s actually a fairly approachable project if you’re looking to make one yourself.
After testing that the IR communication would actually work as expected underwater, [Peter] liberated the motors and electronics from the helicopter. The motor’s wires were shortened, and the receiver PCB got a slathering of epoxy to try and keep the worst of the water out, but otherwise they were unmodified.
If you’re wondering how the ballast system works, there isn’t one. The 3D printed body angles the motors slightly downwards, so when the submarine is moving forward it’s also being pulled deeper into the water. There aren’t any control surfaces either, differential thrust between the two motors is used to turn left and right. This doesn’t make for a particularly nimble craft, but in the video after the break it certainly looks like they’re having fun with it.