Every day we humans hang out and think nothing of the air that is all around us. It is easy to forget that the air has mass and is pulled down to the earth by gravity creating an ambient pressure of about 14.7 psi. This ambient pressure is the force that crushes a plastic bottle when you lower the internal pressure by sucking out the air. [Prof Stokes] from Brigham Young University has used this powerful ambient air pressure as the power source of his ping pong ball cannon.
Instead of filling a reservoir tank with compressed air and using that to fire a projectile, this canon has the air removed from the barrel to create the pressure differential that propels the ping pong ball. The ball is put in one end of a 10 ft long tube. That end of the tube is then covered by a sheet of Mylar. The other end is covered with the bottom of a disposable plastic cup. A vacuum pump is then used to remove the air inside the tube and it is this pressure differential that keeps the plastic cup secured to the end of the tube. When it’s firing time, a knife is used to cut the Mylar at the ping-pong-ball-end of the tube. Air rushes in to fill the vacuum and in doing so accelerates the ping pong ball towards the other end. There is a large jar at the business-end of the cannon that catches the ping pong ball and contains the shrapnel created during the ball’s rapid deceleration!
Since this was a science experiment at a university, some math was in order. Based on the atmospheric pressure and ball cross sectional area, the calculated speed was 570 meters/second or about 1300 mph. The calculations didn’t take into account leakage between the ball and the tube or viscosity of the air so a couple of lasers were set up at the end of the cannon to measure the actual speed – 600 mph. Not too bad for just sucking the air out of a tube!
The office environment over at [Adam]’s place of employment has recently become one of the many IT-related offices with a ping pong table, a cliché that he readily points out. However, [Adam] and the other folks at the office decided to step up their game a little bit by making this automated ping pong table.
The table first keeps track of the players with specialized RFID tags that are placed in the handle of the paddles. The paddles are unique to each player, and when they are swiped past a reader on the table the scoring system registers the players at the table.
Small capacitive touch sensors on the underside of the table allow the players to increment their score when a point is made. The scoreboard is a simple but a very well-polished interface that has audio cues for each point. The system is also able to keep track of the winners and the overall records are tracked, allowing for office-wide rankings.
This is the best table-related game hack since the internet-connected foosball table, and should be welcome in any office for some extra break room fun at work! All of the code is available on the project site.
Well — you guys were right. As it turns out, it was actually a pair of animators who fooled the internet.
Not sure what we’re talking about? Last month, the [Kuka Robot Group] put out a highly polished video showing an industrial robot playing table tennis against the apparent world champion of the sport — it was extremely well done and entertaining to watch, but unfortunately… also fake. Weeks after the first [Kuka] video came out, someone named [Ulf Hoffmann] released another video, a small table tennis playing robot that looked almost feasible.
As some of our readers pointed out:
The movements seemed unnatural for the size of the servos and arm structure. ~ James
CGI. As others have pointed out, the shadow of the arm disappears when the robot is show from the side, even though they were added in the other shots. ~ Brandon
My cgi tip off was the cable under the table. It stretches instead of sliding around. ~ Aj
Notice it’s running Outlook Express and Internet Explorer – no self respecting hacker/maker would run those apps – lol. ~ vonskippy
Continue reading “The Amazing Ping-Pong Robot was Fake”
Would you like to play a robot in ping pong (translated)? We sure would. Inspired by an upcoming face-off between man and machine, [Jakob] wrote in to tell us about [Ulf Hoffmann’s] ping-pong playing robot. If you ever wanted to play ping-pong when no one else was around or are just sick and tired of playing against the same opponents this project is for you. Boy is this thing amazing; you simply must see the robot in action in the video after the break.
While the robot’s build is not documented all in one post, [Ulf Hoffmann’s] blog has many videos and mini posts about how he went about building the paddle wielding wonder. The build runs the range from first ideas, to hand-drawn sketches, to the technical drawings seen above. From these the parts of the arm were built, but the mechanical assembly is only one portion of the project. It also required software to track the ball and calculate how to properly return it. Be sure to browse through his past posts, there is a wealth of information there.
Also be sure to check in on March 11th to see who wins the epic face-off between man and machine. See the trailer (the second embedded video) after the break.
UPDATE: Many commentators are calling this one a fake. It’s so sad to think that, because this is a really cool project. But we’ve changed the title and are asking you to weigh in on whether you think it is real or fake. We’ve also contacted [Ulf] and asked if it is real hardware, or a CGI enhanced video. We’ll let you know if/when we hear back from him.
Continue reading “Real or Fake? The Amazing Ping-Pong Robot”
Next time you’re in a Nerf gun battle, you better hope you’ve got this absurdly powerful ping pong ball gun. It shoots common celluloid spheres at over 400 meters per second, or Mach 1.2.
This ping pong gun is the work of [Mark French], [Craig Zehrung], and [Jim Stratton] at Purdue University. As you would expect, the gun is powered by compressed air housed in a length of 3 inch schedule 80 PVC pipe. One end of the pressure vessel is sealed with a PVC end cap, while the other is closed off with a doubled up piece of duct tape to contain the pressure.
The interesting bit of the build is a de Laval nozzle between the pressure vessel and the barrel. Just like a rocket engine nozzle, this bit of machined PVC compresses the air coming through the burst duct tape seal and allows it to expand again, propelling the muzzle-loaded ping pong ball at supersonic speeds.
The guys have written a report on their gun, you can grab that over on arxiv.
This is just one example of several pairs of spooky eyes which light up [Vato Supreme’s] bushes this Halloween. The quick and inexpensive build process make it a perfect diy decoration.
Each eye is made up of a ping-pong ball and an LED. But that alone won’t be very spook as the entire ball will glow rather brightly. So he spiced things up a bit by masking off the shape of a pupil and spraying the balls black. The vertical slit seen in white above will glow red like a demon in the night.
The LEDs are driven by an ATtiny85 running the Arduino bootloader. [Vato] found there was plenty of space two write code which fades the eyes in and out using PWM. This happens at random intervals for each of the four pairs he is driving.
We’ve seen a similar project that used oversized LEDs as the eyes. But we really like the idea of using a diffuser like this one. See it in action after the break.
Continue reading “Halloween Props: Spooky eyes light up the bushes”
Beer Pong seems to have been around for some time but it only recently exploded in to a universally known game. But one thing has always bothered us. Who wants to drink the beer into which that grimy little ball has fallen? Leave it to the frat boys at MIT to come up with a solution. Their beer pong table automatically cleans your balls.
Of course the table looks great. It’s outfitted with laser cut felt lettering on the apron, and the top features EL wire highlights. But the two features that really set it apart aren’t hard to spot either. First, there are rain gutters along either side to help catch the spillage. Secondly, that blue ring is actually the input nozzle for the ball cleaner. By pushing the ball through the vinyl sleeve it enters a recirculating liquid cleanser, popping out of the portal on the left a second later. That’s about all the details we have on the system, but you can get a closer look at the inner workings in the clip after the break.
The thing to remember is that these guys NEVER run out of ping-pong balls. They’ve got thousands on hand ever since they built this launcher.
Continue reading “Fancy beer pong table cleans your balls”