Ping Pong Ball-Juggling Robot

There aren’t too many sports named for the sound that is produced during the game. Even though it’s properly referred to as “table tennis” by serious practitioners, ping pong is probably the most obvious. To that end, [Nekojiru] built a ping pong ball juggling robot that used those very acoustics to pinpoint the location of the ball in relation to the robot. Not satisfied with his efforts there, he moved onto a visual solution and built a new juggling rig that uses computer vision instead of sound to keep a ping pong ball aloft.

The main controller is a Raspberry Pi 2 with a Pi camera module attached. After some mishaps with the planned IR vision system, [Nekojiru] decided to use green light to illuminate the ball. He notes that OpenCV probably wouldn’t have worked for him because it’s not fast enough for the 90 fps that’s required to bounce the ping pong ball. After looking at the incoming data from this system, an algorithm extracts 3D information about the ball and directs the paddle to strike the ball in a particular way.

If you’ve ever wanted to get into real-time object tracking, this is a great project to look over. The control system is well polished and the robot itself looks almost professionally made. Maybe it’s possible to build something similar to test [Nekojiru]’s hypothesis that OpenCV isn’t fast enough for this. If you want to get started in that realm of object tracking, there are some great projects that make use of that piece of software as well.

Remote Controlling A Dog

Until the industrial revolution, humans made use of animals to make our labor easier. This is still seen in some niche areas, like how no machine yet has been invented that’s as good at sniffing out truffles as pigs are. [William] has hearkened back to humanity’s earlier roots, but in a more modern twist has made something of a general purpose dog that could feasibly do any work imaginable. Now his dog is remote-controlled.

[William] accomplished the monumental task in a literally cartoonish fashion using the old trope of hanging a hot dog in front of something’s face to get them to chase it. The attachment point was fitted with a remote control receiver and an actuator to get the hanging hot dog to dangle a little bit more to the dog’s right or left, depending on where the “operator” wants the dog to go. [William]’s bulldog seems to be a pretty good sport about everything and isn’t any worse for wear either.

Believe it or not, there has been some actual research done into remote controlling animals, although so far it’s limited to remote-controlled cockroaches. We like the simplicity of the remote-controlled dog, though, but don’t expect to see these rigs replacing leashes anytime soon!

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Illuminating New Take on Magnetic Switches

While there’s something to be said for dead-bug construction, hot glue, and other construction methods that simply get the job done, it’s inspiring to see other builds that are refined and intentional but that still hack together things for purposes other than their original intent. To that end, [Li Zanwen] has designed an interesting new lamp that uses magnets to turn itself on in a way that seems like a magnetic switch of sorts, but not like any we’ve ever seen before.

While the lamp does use a magnetic switch, it’s not a traditional switch at all. There are two magnetic balls on this lamp attached by strings. One hangs from the top of the circular lamp and the other is connected to the bottom. When this magnet is brought close to the hanging magnet, the magnetic force is enough to both levitate the lower magnet, and pull down on a switch that’s hidden inside the lamp which turns it on. The frame of the lamp is unique in itself, as the lights are arranged on the inside of the frame to illuminate the floating magnets.

While we don’t typically feature design hacks, it’s good to see interesting takes on common things. After all, you never know what’s going to inspire your next hackathon robot, or your next parts drawer build. All it takes is one spark of inspiration to get your imagination going!

The Electrical Grid Demystified

Our society needs energy, and lots of it. If you’re reading this then the odds are astronomically good that you’re on a computer somewhere using energy, with the power cord plugged into the mysterious “black box” that is the electrical grid. The same is true if you’re reading this on a laptop or phone, which was charged from said black box even though it may not be connected at this moment. No matter where you are, you’re connected to some sort of energy source almost all the time. For almost every one of us, we have power lines leading up to our homes, which presumably connect to a power plant somewhere. This network of power lines, substations, even more power lines, and power plants is colloquially known as the electrical grid which we will be exploring in a series of articles.

While the electrical grid is a little over a century old, humanity has been using various energy sources since the agricultural revolution at least. While it started with animal fat for candles, wind for milling grain, and forests for building civilizations, it moved on to coal and steam during the industrial revolution and has ended up in a huge interconnected network of power lines connected to nuclear, natural gas, coal, solar, and wind sites around the world. Regardless of the energy source, though, there’s one reason that we settled on using electricity as the medium for transporting energy: it’s the easiest way we’ve found to move it from place to place.

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Baby’s First Hands-Free Stroller

So you’ve had your first child. Congratulations; your life will never be the same again. [Dusan] was noticing how the introduction of his children into his life altered it by giving him less time for his hobbies in his home laboratory, and decided to incorporate his children into his hacks. The first one to roll out of his lab is a remote-controlled baby stroller.

After some engineering-style measurements (lots of rounding and estimating), [Dusan] found two motors to drive each of the back wheels on a custom stroller frame. He created a set of wooden gears to transfer power from the specialized motors to the wheels. After some batteries and an Arduino were installed, the stroller was ready to get on the road. At this point, though, [Dusan] had a problem. He had failed to consider the fact that children grow, and the added weight of the child was now too much for his stroller. After some adjustments were made (using a lighter stroller frame), the stroller was eventually able to push his kid around without any problems.

This is an interesting hack that we’re not sure has much utility other than the enjoyment that came from creating it. Although [Dusan]’s kid certainly seems to enjoy cruising around in it within a close distance to its operator. Be sure to check out the video of it in operation below, and don’t forget that babies are a great way to persuade your significant other that you need more tools in your work bench, like a CNC machine for example.

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Portable RetroPie Builds on the Shoulders of Giants

For anyone wanting to get that shot of nostalgia without the hassle of finding an NES Classic, the Retropie project is a great starting point. Of course, it’s not too noteworthy to grab a Raspberry Pi, throw a pre-built distribution on it, and plug in an SNES to USB converter. What is noteworthy, however, is building a Retropie that’s portable and that has the quality and polish of the latest build from [fancymenofcornwood].

render-blowup-of-retropieFor starters, the laser cut wood case was custom-made. From there, all of the PCBs were fitted including specific ones to handle each set of buttons (complete sets of D-pads, shoulder buttons, and joysticks) and another for the 5″ HDMI screen. It has stereo speakers and its own headphone jack (to the envy of all new iPhone owners), and is powered from a Raspberry Pi 2 running Retropie 4.1. The battery pack shouldn’t leave you stranded, either, especially not if you grew up playing the Sega Game Gear.

The quality of the build here is outstanding, and its creator made a design choice to make it easily replicable, so if you’ve wanted to play N64 or PS1 games while on the go, this might be what you’ve been waiting for. There are lots of other options for getting some fun from a Retropie going though, from building one into a coffee table to re-purposing that infamous Game Gear.

Obligatory clip of this portable playing Doom is found after the break.

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Ardu McDuino Plays the Bagpipes

To “pipe in” the new year, [John] decided to build a bagpipe-playing robot. Unlike other instrument-playing robots that we’ve seen before, this one is somewhat anatomically correct as well. John went the extra mile and 3D printed fingers and hands to play his set of pipes.

The brains of the robot are handled by an Arduino Mega 2560, which drives a set of solenoids through a driver board. The hands themselves are printed from the open source Enabling the Future project which is an organization that 3D prints prosthetic hands for matched recipients, especially people who can’t otherwise afford prosthetics. He had to scale up his hands by 171% to get them to play the pipes correctly, but from there it was a fairly straightforward matter of providing air to the bag (via a human being) and programming the Arduino to play a few songs.

The bagpipe isn’t a particularly common instrument (at least in parts of the world that aren’t Scottish) so it’s interesting to see a robot built to play one. Of course, your music-playing robot might be able to make music with something that’s not generally considered a musical instrument at all. And if none of these suit your needs, you can always build your own purpose-built semi-robotic instrument as well.

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