[youtube=http://www.youtube.com/watch?v=sO2-tqoyGik]
Take a few moments and watch this 3 axis rotating LED light display fire up. The final effect of being an RGB glowing ball is nice, but we’re fascinated with the structure. There are tons of great detailed pictures of the assembly on the forum thread to feast your eyes on. Just getting power to the LEDs was a feat, he passes their power through 6 slip contacts. Parts were pulled from an old VCR and some old fans.
[via HackedGadgets]
If you march sufficiently deep into the wilderness of control theory, you’ll no doubt encounter the inverted pendulum problem. These balancing acts have emerged with a number of variants over the years, but just because it’s been done before doesn’t mean there’s no space for something new. Here, [David Gonzalez], has taken this classic problem and given it an original own spin–literally–where the balancing act is now a ball balanced precariously upon a spinning wheel. (Video, embedded below.) Mix in a little computer vision for sensing, a dash of brushless motor control, a bit of math, and you have yourself a closed-loop system that’s bound to turn a few heads.
[David’s] implementation is a healthy mix of classic control theory with some modern electronics. From the theory bucket, there’s a state-space controller to drive both the angle and angular velocity of the ball to zero. The “state” is a combination of four terms: the ball angle, the ball’s angular velocity, the wheel angle, and the wheel’s angular velocity. [David] weights each of these terms and sums them together to create an input value to adjust the motor velocity driving the wheel and balance the ball.
From the electronics bin, [David] opted for an ESP32 running Arduino, the custom Janus Brushless Motor Controller running SimpleFOC, and a Maix Bit Microcontroller with an added camera running MicroPython to compute the ball angle. Finally, if you’re curious to dig into the source code, [David] has kindly posted the firmware on Github.
We love seeing folks mix a bit of control theory into an amalgamation of familiar electronics. And as both precision sensors and motor controllers continue to improve, we’re excited to see how the landscape of projects changes yet again. Hungry for more folks closing the loop on unstable systems? Look no further than [UFactory’s] ball balancing robot and [Gear Down for What’s] two wheeled speedster.
Continue reading “Ball Balancing Wheel Puts A Spin On Inverted Pendulums”
Hackaday editors Mike Szczys and Elliot Williams celebrate the 100th episode! It’s been a pleasure to marvel each week at the achievements of awesome people and this is no different. This week there’s a spinning POV display that solves pixel density and clock speed in very interesting ways. A macro keyboard made of OLED screens gives us a “do want” moment. And you can run a Raspberry Pi photo frame by sipping power from ambient light if you use the right power-tending setup. We wrap up the last episode of 2020 with a dive into ballpoint pens and solar racers.
Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!
Direct download (~65 MB)
Translating rotary motion to linear motion is a basic part of mechatronic design. Take a look at the nearest 3D-printer or CNC router — at least the Cartesian variety — and you’ll see some mechanism that converts the rotation of the the motor shafts into the smooth linear motion needed for each axis.
Hobby-grade machines are as likely as not to use pulleys and timing belts to achieve this translation, and that generally meets the needs of the machine. But in some machines, the stretchiness of a belt won’t cut it, and the designer may turn to some variety of screw drive to do the job.
Even if you don’t like disco, you might like the slick moves that went into this project. [W&M] built a miniature motorized mirror ball inside of a standard incandescent light bulb, and the results are something to dance about.
Short of blowing a glass bulb, building a motor, and growing the wood, this is about as scratch-built as it gets. Much of the woodworking is done on a metal lathe, and this includes the base of the mirror ball itself. As with all good thing-in-a-bottle builds, the ball is too big to go in the bulb, so [W&M] quartered it, drilled a few holes, and ran a string through the pieces so they can be carefully glued and drawn back together into a sphere. He even cut up mirror tiles and painstakingly applied them with tweezers.
This disco bulb is meant to be hung from the ceiling and wired into mains like a regular mirror ball. [M&W] stuffed the guts from a small USB wall charger into the handmade beech base to provide clean power for both the geared motor that spins the ball and the tiny LED that illuminates it. Slip into your best leisure suit (or sweat suit, we won’t judge) and hustle past the break to watch the build video.
We don’t see a lot of disco balls around here, but we did see a disco icosahedron once.
Like many people, going through university followed an intense career building period was a dry spell in terms of making things. Of course things settled down and I finally broke that dry spell to work on what I called “non-conventional propulsion”.
I wanted to stay away from the term “anti-gravity” because I was enough of a science nut to know that such a thing was dubious. But I also suspected that there might be science principles yet to be discovered. I was willing to give it a try anyway, and did for a few years. It was also my introduction to the world of high voltage… DC. Everything came out null though, meaning that any effects could be accounted for by some form of ionization or Coulomb force. At no time did I get anything to actually fly, though there was a lot of spinning things on rotors or weight changes on scales and balances due to ion propulsion.
So when a video appeared in 2001 from a small company called Transdimensional Technologies of a triangle shaped, aluminum foil and wire thing called a lifter that actually propelled itself off the table, I immediately had to make one. I’d had enough background by then to be confident that it was flying using ion propulsion. And in fact, given my background I was able to put an enhancement in my first version that others came up with only later.
For those who’ve never seen a lifter, it’s extremely simple. Think of it as a very leaky capacitor. One electrode is an aluminum foil skirt, in the shape of a triangle. Spaced apart from that around an inch or so away, usually using 1/6″ balsa wood sticks, is a very thin bare wire (think 30AWG) also shaped as a triangle. High voltage is applied between the foil skirt and the wire. The result is that a downward jet of air is created around and through the middle of the triangle and the lifter flies up off the table. But that is just the barest explanation of how it works. We must go deeper!
Continue reading “Expanding Horizons With The Ion Propelled Lifter”
[James Bruton] has just finished and posted the designs for his very impressive BB-8 robot build. We covered the start of his adventures some time ago when we were theorizing about the secret in the new droid, but it was for a completely different robot design. [James] was pursuing a design that used a little robot sitting on top of a big ball.
This new version has a robot sitting inside a ball with the head being magnetically coupled to the body. Among many things with this build, we thought it was cool how the robot has one drive motor and turns by spinning up and reversing a big flywheel in the base of the robot. That was certainly not one of the top theories proposed for the secret behind the robot. The robot is mostly made with a 3d printer, with the occasional cosmetic piece being vacuum formed. If you’d like to make one for yourself, [James] has also posted all of the design and cad for the robot on his GitHub. On Thursday he posted the final installment of his 10-part video series on the build. Check out part one after the break.
