Galactic Dimension – a supersized DIY pinball machine

If you are from the 1960’s or 1970’s we know you would have enjoyed furiously punching the buttons of a pin ball machine back in the day. Installation artist [Niklas Roy] recently revisited this old classic game and built Galactic Dimension – a supersized pinball machine for Phæno – an amazing science center in the German city of Wolfsburg. The science centre was planning a big exhibition featuring thirty beautiful, classic pinball machines loaned from the Pacific Pinball Museum in Alameda, California.

The game machine was built on a steep ramp and has a gigantic play field measuring 3m x 6m (10’x20′). It features Sci-Fi game elements in the play field which blend perfectly with the futuristic building where it is housed. The game elements are built from repurposed everyday items like hair dryers and fans, giving visitors the motivation to build some of their own such contraptions.

The players operate the machine via a control desk, and a giant calculator is used to display the game score. The steep ramp had an incline of almost 30° which meant that he had to use a light ball to be able to propel it around the play field. The main user controls are the two flippers, and building giant ones was a big challenge. Solenoids or coils would not cut the ice, and he settled for pneumatic cylinders – easy to control, powerful, not too loud, and the museum already had a compressed air supply readily available. But it still took him three iterations before he could get it right. The plunger, which initially propels the ball, was built from PVC pipes and a hair dryer. Each play field element was built as a separate module to make assembly and maintenance easier. All featured a 220V AC supply, a sensor (either an IR distance sensor or a light barrier) to detect the ball, and an Arduino. Actuators were built from hair dryers and portable fans. Each of them have their own sound effects too – either a hacked toy or a speaker controlled by the Arduino. After everything was built, taken apart, transported, and reassembled at the site, the Galactic Dimension worked without a glitch, and without releasing any magic smoke. To top it off, Andreas Harre, who’s been the German pinball champion for several years in a row, also played the machine when he visited Phæno – and was totally excited about it!

So if you are in that part of Germany anytime until September, do drop in and try to ring up a big score. For photos of his build log, check out the photo album. There’s also a fairly big block diagram (German) and the Arduino sketches (.zip file), if you’d like to take a stab at building an even bigger pinball machine. Check the video to see the machine in action. And if the name [Niklas] sounds familiar, it is because he loves building installations such as the Forbidden Fruit Machine, the Ball Sucking Machine, and another Ball Sucking Machine.

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Automated Plant Watering System Uses Car Parts

[Shane] recently built an automated plant watering system for his home. We’ve seen several similar projects before, but none of them worked quite like this one. Shane’s system is not hooked into the house plumbing and it doesn’t use any off-the-shelf electronic valves.

Instead, [Shane’s] build revolves around a device that looks like it was intended to spray weed killer. The unit works sort of like a Super Soaker. The user fills the jug with water and then pumps a handle multiple times to build up some pressure inside the jug. Then a button can be pressed and the air pressure forces water out of the nozzle. [Shane] came up with a way to automate all of these mechanical motions.

First [Shane] had to find a way to pump up the bottle. He purchased a car door electronic lock actuator from eBay. It’s a pretty simple device. It’s just a DC motor with a gear box that turns the rotational motion of the motor into linear motion. This is mounted to a wooden jig and attached to the pump. A dsPIC microcontroller rotates the motor back and forth, which in turn pumps up the bottle.

The dsPic is also hooked up to a small servo. The servo is mounted to the same wooden jig as the car door actuator. A small arm is mounted to the servo so that when it rotates, the arm presses the pressure release button. This sends the water out of the bottles nozzle. [Pat] hooked up a small length of hose to the nozzle so he can direct the water into his plants. The video below demonstrates how the unit works. Continue reading “Automated Plant Watering System Uses Car Parts”

Twisted String Actuators

[Travis] tells us about a neat actuator concept that’s as old as dirt. It’s capable of lifting 7kg when powered by a pager motor, and the only real component is a piece of string.

The concept behind the twisted string actuator, as it’s known to academia, is as simple as putting a motor on one end of a piece of string, tying the other end off to a load, and putting a few twists in the string. It’s an amazingly simple concept that has been known and used for thousands of years: ballistas and bow-string fire starters use the same theory.

Although the concept of a twisted string actuator is intuitively known by anyone over the age of six, there aren’t many studies and even fewer projects that use this extremely high gear ratio, low power, and very cheap form of linear motion. A study from 2012 (PDF) put some empirical data behind this simple device. The takeaway from this study is that tension on the string doesn’t matter, and more strands or larger diameter strands means the actuator shrinks with a fewer number of turns. Fewer strands and smaller diameter strands take more turns to shrink to the same length.

As for useful applications of these twisted string actuators, there are a few projects that have used these systems in anthropomorphic hands and elbows. No surprise there, really; strings don’t take up much space, and they work just like muscles and tendons do in the human body.

Thanks [ar0cketman] for the link.

biological-inspired robotic eye movements

Researchers at Georgia Tech have developed a biologically inspired system to control cameras on board robots that simulate the Saccadic optokinetic system of the human eye. Its similarity to the muscular system of the human eye is uncanny.

Joshua Schultz, a Ph.D candidate, says that this system has been made possible in part to piezoelectric cellular actuator technology. Thanks to the actuators developed in their laboratory it is now possible to capture many of the characteristics associated with muscles of the human eye and its cellular structure.

The expectation is that the piezoelectric system could be used for future MRI-based surgery, furthering our ability to research and rehabilitate the human eye.

[via engadget]

Adding power trim to a boat

[Matt’s] boat had a trim plate that could be adjusted by hand. The problem with this setup is that the trim angle of a boat changes as you speed up or slow down. Last year he never really went over 35 MPH because of this issue, but he set out to correct that by adding power trim plates for the upcoming boating season.

The original trim plate didn’t have a hinge on it, but simply flexed when tension was added to the adjustment hardware. [Matt] removed the plate and cut it into three parts; one long thin strip to serve as a mounting bracket, and two plates to independently adjust trim for the left and right side of the keel. Some aluminum strip hinges connect the three pieces, and a pair of used actuators acquired from eBay automate the trim adjustment. Each plate is strengthened by a pair of angle brackets, which also serve as a mounting point for the actuators. The final step was to add a pair of switches near the throttle lever which are used to make manual adjustments when the boat is in motion.

Domino Clock uses an electromechanical display

This clock concept uses big dominos with changing faces to display the time. As far as we can tell they haven’t made it through to a finished product yet, but we loved the explaination of the engineering that went into the prototype. After the break you can watch [Eric] explain how he accomplished the design requirements of a slowly changing digit that uses no power to keep its state, which also uses low-power when changing state. To accomplish this he designed a flipping circle that stays put in both the white and black positions once set. When it’s time to change the digits, a coil is energized to push against a magnet in what he calls a single poled motor. Whatever the name, we want to build one ourselves!

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