A Teensy 4.1 or Teensy 3.2 is used to power [Kevin]’s various singing fish builds. There are two motors inside a singing fish, typically — one motor to pivot the fish’s body, and one to open and close the mouth. Hook these up to a motor driver, and command that with the Teensy, and you’re up and running. To sync the fish with the music, MIDI data is sent to the Teensy over USB. The Teensy takes in note data and uses this to command the motors to make the fish appear to sing along.
The tutorial linked above is a great way to learn how the hack was achieved. However, the real money is in the performance. A video of [Kevin]’s fishy chorus performing the famous Wellerman sea shanty has over 50 million views on YouTube and he’s collected over 26 million likes on Tiktok.
Sometimes the simple hacks are the ones that bring the most joy. Video after the break.
Though some of us are heavily assisted by smart phone apps and delivery, humans don’t need GPS to find food. We know where the fridge is. The grocery store. The drive-thru. And we don’t really need a map to find shelter, in the sense that shelter is easily identifiable in a storm. You might say that our most important navigation skills are innate, at least when we’re within our normal environment. Drop us in another city and we can probably still identify viable overhangs, cafes, and food stalls.
Utah is a place that features a wonderful and varied wilderness. Its mountainous terrain is home to many valleys, ponds, and streams. They’re a particular favorite of recreational anglers who visit the region for the great fishing. Oftentimes, however, these areas are fished out by visitors and need to be restocked. Other environmental factors also come into play in reducing populations, too.
When this happens in some areas, it’s as simple as driving up a truck full of water and fish and dumping them into the lake. The problem is that many of these lakes and streams are difficult to access by foot or by road. Believe it or not, the most practical method found to deal with the problem thus far is dropping in live fish by air. Here’s how it all goes down.
Typically, the fish dropped into these remote watercourses are quite young, and on the order of 1-3″ long. The fish are specifically raised to later be fished, and are also usually sterile, making it easier for Utah’s Division of Wildlife Resources to manage numbers. When it comes time to restock remote lakes, waterbombing planes are pumped full of water and loaded up with fish.
Sisyphus is cursed to roll a boulder up a hill for eternity. Pet fish generally content themselves to swimming the same lap over and over in a glass tank. Perpetuity can be soothing, so long as you’re not shouldering a boulder.
[Zach Frew] wants to integrate and automate the boulder on a smaller scale and one that can benefit his aquarium full of colorful Taiwanese bee shrimp. Instead of an inert rock and a Greek, Sisyphish uses a magnet and servo motors connected to a microcontroller to draw Spirograph-style shapes in the tank’s sand.
There are a couple of gears beneath the tank to trace the geometric patterns but they’re clear of any water. One gear rotates about the center of the cylindrical tank while the other holds a magnet and adjusts the distance from the center. Pilots, and select nerds, will recognize this as rho-theta positioning. Despite the uncommon coordinate system, the circular plotter accepts G-code. We love when math gets turned into gorgeous designs, and shrimp love when those tasty microbes get shaken from their gravelly hiding places.
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.
On Unix — the progenitor of Linux — there was /bin/sh. It was simple, by comparison to today’s shells, but it allowed you to enter commands and — most importantly — execute lists of commands. In fact, it was a simple programming language that could make decisions, loop, and do other things to allow you to write scripts that were more than just a list of programs to run. However, it wasn’t always the easiest thing to use, so in true Unix fashion, people started writing new shells. In this post, I want to point out a few shells other than the ubiquitous bash, which is one of the successors to the old sh program.
Since the 7th Edition of Unix, sh was actually the Bourne shell, named after its author, Stephen Bourne. It replaced the older Thompson shell written in 1971. That shell had some resemblance to a modern shell, but wasn’t really set up for scripting. It did have the standard syntax for redirection and piping, though. The PWB shell was also an early contender to replace Thompson, but all of those shells have pretty much disappeared.
You probably use bash and, honestly, you’ll probably continue to use bash after reading this post. But there are a few alternatives and for some people, they are worth considering. Also, there are a few special-purpose shells you may very well encounter even if your primary shell is bash.
Every fisherman has a secret. A secret spot, a secret technique, or a secret bait. Maybe that’s why tying flies is so popular. [Steve] certainly has is own special lures, although he’s not keeping it a secret. (Video, embedded below.) He designs lures in Simplify3D, 3D prints molds, and then casts them.
The 3D printing part is interesting, but it is also kind of neat to see the lures and the natural prey he uses for inspiration. If you want to catch fish, you have to use bait that looks like real food.