Pneumatic Launcher Gets Ham Antennas Hanging High

Amateur radio is an eclectic hobby, to say the least. RF propagation, electrical engineering, antenna theory – those are the basics for the Ham skillset. But pneumatics? Even that could come in handy for hanging up antennas, which is what this compressed-air cannon is designed to do.

[KA8VIT]’s build will be familiar to any air cannon aficionado. Built from 2″ Schedule 40 PVC, the reservoir is connected to the short barrel by a quarter-turn ball valve. Charging is accomplished through a Schrader valve with a cheap little tire inflator, and the projectile is a tennis ball weighted with a handful of pennies stuffed through a slit. Lofting an antenna with this rig is as simple as attaching a fishing line to the ball and using that to pull successively larger lines until you can pull the antenna itself. [KA8VIT] could only muster about 55 PSI and a 70′ throw for the first attempt shown below, but a later attempt with a bigger compressor got him over 100 feet. We’d guess that a bigger ball valve might get even more bang for the buck by dumping as much air as quickly as possible into the chamber.

Looking to launch a tennis ball for non-Ham reasons? We’ve got you covered whether you want to power it with butane or carbon dioxide.

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Keeping Humanity Safe from Robots at Disney

Almost every big corporation has a research and development organization, so it came as no surprise when we found a tip about Disney Research in the Hackaday Tip Line. And that the project in question turned out to involve human-safe haptic telepresence robots makes perfect sense, especially when your business is keeping the Happiest Place on Earth running smoothly.

That Disney wants to make sure their Animatronics are safe is good news, but the Disney project is about more than keeping guests healthy. The video after the break and the accompanying paper (PDF link) describe a telepresence robot with a unique hydrostatic transmission coupling it to the operator. The actuators are based on a rolling-diaphragm design that limits hydraulic pressure. In a human-safe system that’s exactly what you want.

The system is a hybrid hydraulic-pneumatic design; two actuators, one powered by water pressure and the other with air, oppose each other in each joint. The air-charged actuators behave like a mass-efficient spring that preloads the hydraulic actuator. This increases safety by allowing the system to be de-energized instantly by venting the air lines. What’s more, the whole system presents very low mechanical impedance, allowing haptic feedback to the operator through the system fluid. This provides enough sensitivity to handle an egg, thread a needle — or even bop a kid’s face with impunity.

There are some great ideas here for robotics hackers, and you’ve got to admire the engineering that went into these actuators. For more research from the House of Mouse, check out this slightly creepy touch-sensitive smart watch, or this air-cannon haptic feedback generator.

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Oscillating Pneumatic Mechanism Doesn’t Need a Purpose

It’s true that a lot of the projects we feature here (and build ourselves) are created to accomplish some sort of goal. But, many times the project itself is the goal. That’s the case with [Proto_G’s] self-oscillating pneumatic machine, which he built with no particular use in mind.

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Zizzy The Personal Robot Uses 3D Printed Artificial Muscles Instead of Hobby Servos

Zizzy is a personal robot designed to help those with limited mobility. Rather than being assisted by a nightmare creature, Zizzy would offer a more appealing and friendly option.

The coolest part about Zizzy is the 3D printable pneumatic artificial muscles. Project creator, [Michael Roybal] said it took over a year of development to arrive at the design.

The muscles are hollow bellows printed out of Ninjaflex with carefully calibrated settings. A lot of work must have gone into the design to make sure that they were printable. After printing the muscles are painted with a mixture of fabric glue and MEK solvent. If all is done correctly the bellows should be able to hold 20 PSI without any problem.

This results in a robot with very smooth and precise movement. It has none of the gear noise and can also give when it collides with a user, a feature typically found only in very expensive motor systems. If [Michael] can find a quiet compressor system the robot will be nearly silent.

Parallel Compressors for Sandblasting without Crashing Your Grid

[Hannah] is restoring a 1962 Volkswagen Bug. The goal is to get the car on the road in time for her driver’s test. This is no easy task, as the lower 3 inches of all the body work is rusted out, and the engine is…. well, missing. Basically, the car needs a frame off restoration. This means that [Hannah] will have a lot of metal bodywork to clean up. One of the easiest ways to do that is sandblasting.

Large scale sandblasting is a bit different from most air-powered operations. Sandblasting needs only a modest air pressure, but a high air flow. [Hannah] need 25 Sustained Cubic Feet Per Minute (SCFM) at 80 PSI for sandblasting. Most compressors can easily supply that pressure, but 25 SCFM is asking quite a lot. She could go with an expensive 3 phase unit, or rent a diesel screw compressor. However, [Hannah] decided to connect 4 compressors in parallel to give her the flow she needed.

Connecting the air outputs in parallel is easy. The problem is the electricity. Each compressor is rated for 9 amps while running. They draw quite a bit more while starting up. The compressors have to be wired to individual 15 amp circuits to avoid blowing fuses. They also need to be started in sequence so they don’t pull down the AC for the entire house while starting.

Hannah could have used any sort of delay for this, but she chose an Arduino. The Arduino’s wall wart is wired up to the master compressor. Turning on the master powers up the Arduino which immediately starts a 2 second delay. When the delay times out, the Arduino fires up the second compressor. After several delay loops, all 4 compressors are running together.

hannah-schThe Arduino’s GPIO pins can’t handle 9 amp AC loads, so [Hannah] wired them to TIP120 transistors. The TIP120s drive low power relays, which in turn drive high current air conditioning relays. The system works quite well, as can be seen in the video below the break.

If you’re interested in air compressor projects, check out this setup made from an old refrigerator compressor. For more background on the TIP120, check out this article about these useful transistors.

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Hackaday Prize Entry: Harmonicas, Candy, And Van Halen

Watch enough How It’s Made, and you’ll soon become very enthusiastic about computer vision and compressed air. In factories all around the world, production lines automatically sort the wheat from the chaff by running a product underneath a camera and blowing defective product off the line.

For his Hackaday Prize entry, [Fabien] is attempting this same task. He’s building a machine that will rapidly sort candy with computer vision and precisely controlled jets of air. He’s also planning for the Van Halen reunion and building a CNC harmonica.

Right now, the design has a hopper full of M&Ms dropping through a channel where a camera looks at each individual piece of candy. A Raspberry Pi, camera, and OpenMV detect all the red, yellow, brown, and blue M&Ms, and send that information to a computer controlling a suite of pneumatic valves. When these valves open, candy of different colors is shuffled off into it’s own bin. It’s the perfect device for someone responsible for reading Van Halen’s rider.

In an interesting little side project, [Fabien] needed a way to test the pneumatic valves before building the color sensor and candy chute. He had a harmonica lying around, and built something we’re surprised we’ve never seen before. It’s a CNC harmonica, capable of belting out a few tunes. You can check out that testing video after the break.

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