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.
While the homebrew rebreather the [AyLo] describes on his blog looks exceptionally well engineered and is documented to a level we don’t often see, he still makes it very clear that he’s not suggesting you actually build one yourself. He’s very upfront about the fact that he has no formal training, and notes that he’s already identified several critical mistakes. That being said, he’s taken his rebreather out for a few dives and has (quite literally) lived to tell the tale, so he figured others might be interested in reading about his experiments.
For the landlubbers in the audience, a rebreather removes the CO2 from exhaled air and recirculates the remaining O2 for another pass through the lungs. Compared to open circuit systems, a rebreather can substantially increase the amount of time a diver can remain submerged for a given volume of gas. Rebreathers aren’t just for diving either, the same basic concept was used in the Apollo PLSS to increase the amount of time the astronauts could spend on the surface of the Moon.
The science behind it seemed simple enough, so [AyLo] did his research and starting designing a bare-minimum rebreather system in CAD. Rather than completely hack something together with zip ties, he wanted to take the time to make sure that he could at least mate his hardware with legitimate commercial scuba components wherever possible to minimize his points of failure. It meant more time designing and machining his parts, but the higher safety factor seems well worth the effort.
The wind turbine’s blades look professional but you’ll be surprised to see that they’re simply cut from a PVC pipe. And they work great. The air compressor is taken from a car and the base of the wind turbine’s tower started life as a bed frame. As you’ll see in the video below, the whole setup is quite effective. It would have been nice to see him using his leg mounted, beer bottle propulsion system at the same time, but the air hose may not have been long enough to make good use of them.
It turns out that this robofish comes from the fertile mind of [Carl Bugeja], whose PCB motors and flexible actuators have been covered here before. The basic concept of these fish fins is derived from the latter project, which uses coils printed onto both sides of a flexible Kapton substrate. Positioned near a magnet, the actuators bend when a current runs through them. The video below shows two prototype robofish, each with four fins. The first is a scrap of foam with a magnet embedded; the fins did flap but the whole thing just weighed too much. Version two was much lighter and almost worked, but the tether to the driver is just too stiff to allow it to really flex its fins.
It looks like it has promise though, and we’re excited to see where [Carl] take this. Perhaps schools of tiny robofish patrolling for pollution?
Someday Elon Musk might manage to pack enough of us lowly serfs into one of his super rockets that we can actually afford a ticket to space, but until then our options for experiencing weightlessness are pretty limited. Even if you’ll settle for a ride on one of the so-called “Vomit Comet” reduced-gravity planes, you’ll have to surrender a decent chunk of change, and as the name implies, potentially your lunch as well. Is there no recourse for the hacker that wants to get a taste of the astronaut experience without a NASA-sized budget?
To construct his underwater VR headset, [spiritplumber] uses a number of off-the-shelf products. The main “Cardboard” headset itself is the common plastic style that you can probably find in the clearance section of whatever Big Box retailer is convenient for you, and the waterproof bag that holds the phone can be obtained cheaply online. You’ll also need a pair of swimmers goggles to keep water from rudely interrupting your wide-eyed wonderment. As for the custom printed parts, a frame keeps the waterproof bag from pressing against the screen while submerged, and a large spacer is required to get the phone at the appropriate distance from the operator’s eyes.
To put his creation to the test, [spiritplumber] loads up a VR rendition of NASA’s Neutral Buoyancy Laboratory, where astronauts experience a near-weightless environment underwater. All that’s left to complete the experience is a DIY scuba regulator so you can stay submerged. Though at that point we wouldn’t be surprised if a passerby confuses your DIY space simulator for an elaborate suicide attempt.