Forget Propellers, Embrace Tentacle-based Locomotion

April 9, 2025 by Donald Papp 25 Comments

Underwater robots face many challenges, not least of which is how to move around. ZodiAq is a prototype underwater soft robot (link is to research paper) that takes an unusual approach to this problem: multiple flexible appendages. The result is a pretty unconventional-looking device that can not only get around effectively, but can do so without disturbing marine life.

ZodiAq sports a soft flexible appendage from each of its twelve faces, but they aren’t articulated like you might think. Despite this, the device can crawl and swim.

With movement inspired by bacterial flagella, ZodiAq moves in an unusual but highly controllable way.

Each soft appendage is connected to a motor, which rotates the attached appendage. This low-frequency but high-torque rotation, combined with the fact that each appendage has a 45° bend to it, has each acting as a rotor. Rotation of the appendages acts on the surrounding fluid, generating thrust. When used together in the right way, these appendages allow the unit to move in a perfectly controllable manner.

This locomotion method is directly inspired by the swimming gait of bacterial flagella, which the paper mentions are regarded as the only example of a biological “wheel”.

How fast can it go? The prototype covers a distance of two body lengths every fifteen seconds. True, it’s no speed demon compared to a propeller, but it doesn’t disturb marine life or environments as it moves around. This method of movement has a lot going for it. It’s adaptable and doesn’t use all twelve appendages at once; so there’s redundancy built in. If some get damaged or go missing, it can still move, just slower.

ZodiAq‘s design strikes us as a very accessible concept, should any aspiring marine robot hackers wish to give it a shot. We’ve seen other highly innovative and beautiful underwater designs as well, like body-length undulating fins and articulated soft arms.

We do notice that since it lacks a “front” — it might be a challenge to decide how to mount something like a camera. If you have any ideas, share them in the comments.

DIY Pipe Inspector Goes Where No Bot Has Gone Before

November 27, 2024 by Dan Maloney 7 Comments

If you think your job sucks, be grateful you’re not this homebrew sewer inspection robot.

Before anyone gets upset, yes we know what [Stargate System] built here isn’t a robot at all; it’s more of a remotely operated vehicle. That doesn’t take away from the fact that this is a very cool build, especially since it has to work in one of the least hospitable and most unpleasant environments possible. The backstory of this project is that the sewer on a 50-year-old house kept backing up, and efforts to clear it only temporarily solved the problem. The cast iron lateral line was reconfigured at some point in its history to include a 120-degree bend, which left a blind spot for the camera used by a sewer inspection service. What’s worse, the bend was close to a joint where a line that once allowed gutters and foundation drains access to the sewer.

To better visualize the problem, [Stargate] turned to his experience building bots to whip up something for the job. The bot had to be able to fit into the pipe and short enough to make the turn, plus it needed to be — erm, waterproof. It also needed to carry a camera and a light, and to be powered and controlled from the other end of the line. Most of the body of the bot, including the hull and the driving gear, was 3D printed from ABS, which allowed the seams to be sealed with acetone later. The drive tracks were only added after the original wheels didn’t perform well in testing. Controlling the gear motors and camera was up to a Raspberry Pi Zero, chosen mostly due to space constraints. An Ethernet shield provided connectivity to the surface over a Cat5 cable, and a homebrew PoE system provided power.

As interesting as the construction details were, the real treat is the down-hole footage. It’s not too graphic, but the blockage is pretty gnarly. We also greatly appreciated the field-expedient chain flail [Stargate] whipped up to bust up the big chunks of yuck and get the pipe back in shape. He did a little bit of robo-spelunking, too, as you do.

And no, this isn’t the only sewer bot we’ve ever featured.

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Cleaning Up World War 2’s Legacy On The Seafloor With Robots

June 28, 2024 by Maya Posch 26 Comments

Until the 1970s, a very common method to dispose of unneeded munitions was to simply tip them off the side of a ship. This means that everything from grenades to chemical weapons have been languishing in large quantities around Europe’s shorelines, right alongside other types of unexploded ordnance (UXO).

Although clearing and mapping such dump sites are a standard part of e.g. marine infrastructure such as undersea cabling and off-shore wind turbines, no large-scale effort has so far been undertaken to remove them, even as they continue to pose an increasing hazard to people and the environment. Most recently, efforts are underway to truly begin clearing these UXO, as the BBC reports.

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Hackaday Links: June 23, 2024

June 23, 2024 by Dan Maloney 9 Comments

When a ransomware attack targets something like a hospital, it quickly becomes a high-profile event that understandably results in public outrage. Hospitals are supposed to be backstops for society, a place to go when it all goes wrong, and paralyzing their operations for monetary gain by taking over their information systems is just beyond the pale. Tactically, though, it makes sense; their unique position in society seems to make it more likely that they’ll pay up.

Which is why the ongoing cyberattack against car dealerships is a little perplexing — can you think of a less sympathetic victim apart from perhaps the Internal Revenue Service? Then again, we’re not in the ransomware business, so maybe this attack makes good financial sense. And really, judging by the business model of the primary target of these attacks, a company called CDK Global, it was probably a smart move. We had no idea that there was such a thing as a “Dealer Management System” that takes care of everything from financing to service, and that shutting down one company’s system could cripple an entire industry, but there it is.

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2022 FPV Contest: Turbo Super Submarine

December 29, 2022 by Jenny List 13 Comments

The projects featured on these pages frequently rule the air, the ground, the rails, and even the waves, but very rarely do they rule the deep. Building a submarine is hard, and thus it’s a challenge not taken on by all but the most courageous of builders. This hasn’t discouraged [Timo] though, who has embarked on the construction of what is shaping up to be a very nice underwater ROV build.

The design is straightforward enough, with a PVC tubing frame carrying thrusters for maneuvering, and a central tubular compartment for the electronics and a camera. Control and power comes via a wired connection, and there is a companion controller holding a Pi Pico interfaced to a PlayStation controller.

So far the craft is a work in progress, and he’s engaged in a battle with water pressure to keep in dry inside. The fittings are all 3D printed, and this means a constant battle with warped prints and collapsing infill. He’s not given up though, and is instead recovering enthusiasm by working on the shore-side controller.

We look forward to seeing this project completed, meanwhile if you’re thirsty for more underwater projects take a look at the glider which won the 2017 Hackaday Prize.

3D Printed ROV Is The Result Of Many Lessons Learned

November 2, 2022 by Danie Conradie 10 Comments

Building an underwater remotely operated vehicle (ROV) is always a challenge, and making it waterproof is often a major hurdle. [Filip Buława] and [Piotr Domanowski] have spent four years and 14 prototypes iterating to create the CPS 5, a 3D printed ROV that can potentially reach a depth of 85 m.

FDM 3D prints are notoriously difficult to waterproof, thanks to all the microscopic holes between the layers. There are ways to mitigate this, but they all have limits. Instead of trying to make the printed exterior of the CPS 5 waterproof, the electronics and camera are housed in a pair of sealed acrylic tubes. The end caps are still 3D printed, but are effectively just thin-walled containers filled with epoxy resin. Passages for wiring are also sealed with epoxy, but [Filip] and [Piotr] learned the hard way that insulated wire can also act as a tube for water to ingress. They solved the problem by adding an open solder joint for each wire in the epoxy-filled passages.

For propulsion, attitude, and depth control, the CPS 5 has five brushless drone motors with 3D printed propellers, which are inherently unaffected by water as long as you seal the connectors. The control electronics consist of a PixHawk flight controller and a Raspberry Pi 4 for handling communication and the video stream to a laptop. An IMU and water pressure sensor also enable auto-leveling and depth hold underwater. Like most ROVs, it uses a tether for communication, which in this case is an Ethernet cable with waterproof connectors.

Acrylic tubing is a popular electronics container for ROVs, as we’ve seen with an RC Subnautica sub, LEGO submarine, and the Hackaday Prize-winning Underwater Glider.

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We All Live In A PVC Submarine

December 11, 2021 by Al Williams 11 Comments

We doubt you could really live in [Pena’s] PVC submarine, but now the song’s stuck in our head anyway. Although the post is in Portuguese, you can get a pretty good idea of how it works, and translation software is better than ever. Transcending the language barrier, there are videos of just about every step of the construction. We didn’t, however, find a video of the vehicle in the water.

The plumber’s delight has modified motors for thrusters, and a camera as well. Epoxy potting keeps things waterproof. We’ve seen candle wax used for the same purpose in other builds.

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